what happened to us? i honestly believe we were envied so much

Hello all, well here is my story and im hoping for any advice possible, sorry if I go on a bit,

Well me and my girlfriend have been going out for 4 years, i am now 27 she is now 21, we had everything special about a relationship, it was honestly the most beautiful perfect relationship you could ever wish for, we shared so so much in common, we are both good tennis players, we spent so much time together playing, I treated her to the world, we was sporty, she even enjoyed watching football and ice hockey with me, let alone my country music obsession we saw so many bands we had so many holidays, we both loved each other unbelievably, we are known for our relationship, people talk about us as there favourite couple,

And now this is where it got messy, at first I got on with her family, I treated them so well, I did so so much for them, I practically run there wedding, I did the photos I did the video I put so much work into making it perfect, I even drove them to the wedding, but when I got home I noticed a very weird feeling of being used, I bought them meals, I had one day where I got an illness round there home, early morning I collapsed at the top of there stairs and needed an ambulance they would not walk 5 steps to help me down the stairs, wouldn’t even open the door to see if im ok, I never got one thank you from any of them after all I did, then she had 2 sisters that I know envied my girlfriends life so much, jealously around them was unbelievable, I helped my girlfriend get a good job, get a car, have savings and they hated it, they took this out on me so much, I even got a beating from her dad for this, and almost 1.5 years ago, I told my girlfriend to just be nice to her family until we can get somewhere to live, she got treated so bad by them you wouldn’t believe, they beat her terribly cut her lip open scratch her body all over kicked her punched her and eventually kicked her out, I had to do something so I moved out and into a new place for her, they tracked us down threatening to burn the house down I was so stressed I couldn’t believe it, lost my hair, but was happy for my girlfriend because she was now happy.

We lived together had a few small arguments where I said go and find somewhere better, she would leave but come back a better person, she is a very easily influenced person, and I believe this is because of the way she was treated when she was younger, I don’t blame her one bit, the times we had together were incredible though, it was so special, no other words can describe it other then just perfect!

We lived for each other, and up until 8 months ago we met a couple that was more then friendly after 20 mins of knowing each other they were asking us round constantly for meals to talk etc, I said I will when I know them better, I tried to like the guy but he was always off with me, and I really mean it, my girlfriend carried on getting on with them,
when i asked what did you get upto tonight when she saw them she would just say they talked for 4 hours, i had an arguement once to her about discussing our relationship with them, she never listened =( they dont seem to have other friends and now its starting to make more and more sense what they were doing, causing trouble between us, my girlfriend would come home and say why cant we be like them, why cant we do this, it got to me everytime, they are no way better then us, they influenced her so much that she was changing. We had another small argument and my girlfriend after it all sorted itself out told me he said he doesn’t understand why she is still with me and if it was him he would do a runner! He just never liked me at all. I swear to god I tried with him, I put my hand on my heart and say I really tried!

2 weeks ago was a amazing week for us, perfect! Then she asked can one sister come over, I didn’t want this to happen but I let her over, my girlfriend was really happy, then the huge blow happened the following morning she said she wants her family back again, my stomach churnd when reading it, not again I thought, I couldn’t possibly go through what I did again, I told her I cant do it again and she simply said that I cant tell her who she can or cant see and I offered her the spare room to think it over, she left before I even got home =( that morning I cuddled her so tight before leaving for work, I loved her so much.
Im completely devastated beyond belief, I haven’t slept for a week, I feel sick all the time! Im so so sad inside, I keep crying, im just at ends wit, my life feels over! =(

I honestly gave her the world, treated her so so well, but the thing is she always appreciated it, we just loved each other so much, we did literally everything together, there wasn’t anything we both didn’t like doing!
Her family have started slowly getting back into her life and with the help of the couple that I know have more then instigated her into thinking it would be a good idea for her to see them again, I really feel so bad for her as they are treating her like a trophy! It hurts me so much, she has gone and I doubt ill ever see her agin, I cant even look at another girl, even last week she asked me that if she said it would break her heart if she ever saw me with another girl, then this happened!
I just don’t know what to do, if I was to ever ask the family what did I do they would never even have an answer, it was pure jealousy, im gutted