It's too late for me now

I broke up with my girlfriend of 4.5 years 6 months ago. I feel incredible guilt for hurting her, for not being there for her when she needed a friend. I hate myself now and i wish i could travel back in time.

I was frustrated, we had no physical intimacy, i was addicted to porn and wasn't really present. For a long time i was not able to feel joy in life even after finishing my degree i wasn't happy and i never get excited for anything nor i'm unable to cry even when i would love to get those feelings off my chest.

I miss our peace and our home, i hate myself for it. I have ruined something stable even tho sometimes i felt like she was unnecessary mean to me and didn't rly want to do things with me even when i tried talking her over multiple times. When i broke up with her she was nice to me but crushed, she wanted to fix things and i was in denial, she wanted to go to therapy together but i declined and now i feel like i ruined my life because when i look back she always appreciated me and was there for me when i needed her the most.

Now she went through therapy and found someone else saying she is happy now, yet i miss what we had and would do anything to have it back.

I keep getting anxiety attacks pretty often Now and hope i can work on myself. I start my first therapy session tomorrow, wish me luck.