(Long read) What should i do? im confused about my break up!

Me and my ex girlfriend were in a 3 year relationship until she broke up with me in september, everything was going great until 1 year and 7 months into the relationship when i broke up with her because my head was cooked because i found out my mother had cancer and i was worried about life etc... i realised i made a mistake and got her back and things were good again then things became bad when i got a new job where i worked long hours and couldnt see her in the week and my mother passed away from cancer...

I brought it on myself because i became a different person things happened and i wasnt doing things to make things work between us to much was going on in my life to even be concerned about us. She did tell me that she wasnt happy but it didnt register with me because i had things on my mind like my mother having cancer, work etc..

Realising my mistakes i became paranoid and aggressive towards her which pushed her over the edge when i accused her of cheating and i screamed at her down the phone. Next day she broke up with me said that shes had enough and i wasnt the same person.

I tried getting her back i tried chasing her and begging but that didnt work, My temper still showed at times when she was rejecting me. Then about 3 weeks after we broke up she told me she started meeting someone else so that really did it for me, at first i tried to keep my cool but eveytime i was in her company i could feel myself shaking with rage even though its not what i wanted me to feel like.

This really pushed me over the edge i became desperate, angry and obsessive until one day i finally cracked i even threatened suicide (STUPID I KNOW). After that i realised i needed to get help because i was a emotional wreck.

I under went counselling and i didnt talk to her for like 3 weeks i knew that i needed to fix myself and to get help so i could control my emotions also get closure on a few things thats happened to me which makes me react the way i do to certain things.

I could tell i was making progress because i seen this new guy shes been seeing in a nightclub and old me would of assaulted him but instead i walked up to him (drunk) shook his hand and told him "look after her shes a great girl and your a nice guy i wish you all the best" now this even shocked me when i woke up the next day i felt embarressed but i knew it was the right thing to do.

Few days later i was out again and i seen my ex in a club, i sat down next to her we had a chat and a laugh, i remember her saying that she was shocked that i said what i said to this new guy and that i looked nice etc...

So since the no contact was broke i sent her a message earlier on facebook saying "hey was nice to see you the other night, you ok?" she replied "Yeah its good we can get along, I'm good, how are you?" so the convo went from there we didnt speak for long... i would put the conversation up but it will take up some space lol but the feeling i got was that she didnt care about me going out with other women and that its over.

I really do love this girl and it pains me to see her with this other guy i would love to win her back but is it even worth it i mean she seems to be having a great time with this new guy of hers and i feel as if theres no chance.

I mean 3 years we were together and its come to this, im confused how come shes moved on so soon?

I had to take 2 weeks off in july because of my mother passing and i remember at the end when i was due back in work my ex saying "im gutted you have to go back to work because im going to miss you again and i really loved having you around"

Suggestions please?

Thanks.