hello, hoping someone can help

right, this is a long and complicated one and i just hope someone can make sense of it all.
i was content in life, had a daughter and a 7 year relationship that had endured a lot but never really made me truely happy!
i am 35 and met K who is 23 at work and she was the funniest most beautifull thing id ever seen, we became best of friends working in a secure hospital and laughed and flirted constantly. one night on a works night out we kissed, id never felt feelings like it and can still remember it now as though it was yesterday.
For 3 months we continued to meet and flirt but it never went any further until 1 day i told her i loved her, i did, more than id ever felt for anybody, she admitted she felt exactly the same.
i made a massive decision that broke my heart, i took myself away from everyone for a week and decided i couldnt let the chance of losing my soul mate, so i left my daughter and partner. hardest thing id ever had to do but i was honest and truthfull and have a great relationship with them now and she understand why i left and is getting married next year.
Back to K, we moved straight in together, which put me in debt supportin 2 households but i didnt care, i was on cloud 9, found the woman of my dreams and she felt the same, the next 6 months were amazin, sex, fun, constant textin when we were apart. Then i started to see another side to her, she would be jealous of my daughter, jealous when i went to pick her up, jealous when i talked to any other girls at work. creating arguments for nothing, but then the next day id get the old K back and it was all fine again.
Then next thing she is pregnant, she had taken anti biotics and they had canceled out the pill, she was heartbroken, we had no money, she said she was to young, we contemplated abortion but agreed we couldnt do it.
The house i owned with my ex was free so we moved there, which was an hour away from all her family n friends, but it was all we could do. The jealousy got worse, she never really tried to make friends with my friends as she seen them as my exs friends, we would argue about that, she would say she hated living away from her fam and friends, what could i do, i changed to a better more stressfull job to try and get some money together, she would get upset when she rang me at work and i couldnt talk. i buried my head in the sand and just hoped things would improve, i put the house up for sale and said we could live where she wanted.
Our son was born and i played the doting father, i adored him, surely things would get better now, for a while they did, she told me she loved me everyday through all this and said i didnt show i loved her, the amazing sex had gone to be replaced by the occasional fumble and she said she couldnt argue all day then just have sex?
Our son wouldnt sleep, really needy baby, hard work we were shattered, wed been together nearly 2 years now and though wed had it tough she still lit up my heart, she was still beautifull confident and funny! just the mood swings were confusing me, maybe the hormones from birth? i just carried on kept working hard, buying her nice gifts when money allowed, she still brought me dinner to work, kissed me like she loved me, text me every hour to see how i was.
Then it came to xmas, our son was startin to sleep, work and money were better, a good xmas and we would b back on track. i went on the works night out, she went out with her sister and her new boyfriend and friends. she rang me a t 2am to tell me she was staying over and she loved me and i fell to sleep. next day my life changed for ever, she came home a different person, she was cold, she didnt text me every hour anymore, she talked about her sisters boyfriends friends and how nice they were.
I got suspicous, looked on her facebook and phone and found she had been talking to B quite a lot, so i questioned her, she said he was jsut a friend and she has always been friends with many guys which was true. He listened to her and i didnt anymore, i tried to let it go, but i knew things were not right anymore, we spent x mas day at her mums, she was cold all day, she was somebody else! boxing day morning we were due to go to my parenst for a few days, as i loaded the kids n luggage into the car she laid in bed, i lost it and said she wasnt goin to ruin our sons first xmas anymore and if she didnt buck up i was going without her, to my amazment she said ok.
i spent 4 days at my parents constantly arguing on the phone with her, she said she loved me but wasnt happy anymore and needed some space, for the next 4 months i begged,cried,threatend suicide, i became a mess basically, how could she do this 2 me, i even persuaded her home twice but it lasted days and she left again.
At one stage she got offered emergency housing and said she wouldnt take it if i didnt want her 2 but i said if she felt it was for the best then do it.
she said she wanted more than anything for us to be a family, but then next night she would be out with all her friends, another guy came on the scene D, an old school friend who was like "her brother" i checked phone bills, she had been ringing him often. I remember his name from when our son was born, she mentioned him as a new facebook friend.
She then wanted us to try and be friends and see if we could slowly rebuild our relationship, so we tried, met a few times but i was always sad and asking why, she would get angry and say we cant get on why cant you be happy.
She said she had tried and id took her for granted, shed given up her life for me and i never appreciated it, now id realised how much i loved her it was 2 late cause she didnt feel the same anymore.
About 6 weeks ago, 4 months after xmas i told her i couldnt continue like this, id made a decision she either came back and worked it out or it was over, she chose over, within a week D turned from good friend to new boyfriend. Ive never felt pain like it, id tried dating to make my hurt go away, no chance, made me feel sick, how could she move on??? how could she desert me when i needed her the most????
her parents had split when she was 11 and her dad and 3 older siblings stook together whilst she went with her mother, she played on this and always said she was the black sheep and nobody loved her, she brought this up and says its all her fault, shes incapable of being happy, shes a * * * * up! but surely she loved me and our son enough to be stronger for us???
Anyway shes left for good, decided she doesnt feel the same about me, that im not what she wants, i wake every morning in sweats, imaganing her and D sleeping together, bathing my son together, laughing like we used to, when she hears me upset shes so cold and says lifes too short, shes making the most of her life and so should i.
I cant, i love her, i miss her, even after everything shes done, she lied constantly for 4 months, even swearing on our sons life on 1 occasion and when i found out just laughed and put the phone down, shes constantly on facebook, drunk, partying with her friends and him.
Ive done 4 weeks almost NC, deleted her from facebook, deal with our son through our parents, she texts every couple of days and rings saying our son wants to talk to me but i cant answer, it hurts to much, her new boyfriend even rang this weekend at 1am whilst i was asleep, left me a text saying im a * * * * and he wanted a word, i didnt dare call back cause 1 what i may have heard and 2 i swear i wanted to kill him.
Dont know what im asking for really, just maybe someone who can make sense of it all, i feel like im losing my mind
thanks for reading
L