Loss of friend

I met my best friend almost 26 years ago this month. We had a strange relationship we were more than friends at some times. I remember the first day I saw her I was in trouble. She was the most beautiful and TBH hottest woman I've ever seen. Best personality and we hit it off instantly. Music was our thing- she introduced me to Metallica. We spent endless hours together listening to music, hanging out at bars and getting drunk together. I was married at the time then she was married later on but it didn't slow us down. Years ago she was pregnant and telling me it may be mine. I blew her off because I was in another new relationship. Long story short over the years we found each other time and time again - but I never found out if what she said was true- I was a raging alcoholic at the time. Anyway I haven't seen her for awhile and found out in June she had passed away in May. I was in shock. I cannot get over this grief and guilt I feel now. It's my fault I avoided her recently for reasons I thought were good but I see now they weren't. I was selfish. She needed someone - she died alone and basically gave up on life. I can't stand this. She always took care of me- we never argued. She was the best time of my life. I owed her. I loved her more than anything. Hindsight sucks. I should've been there she had tried to contact me but I didn't respond I had no idea she was that bad. Now I have to live with this I cannot accept what I've done. I've lost most close relatives years ago. I lost my mother when I was 11, my father when I was 17. Honestly their loss doesn't affect me like this. Nothing compares to this grief I'm having now.