Guilt and Regret Over Hurting a Good Woman

I started dating an older woman when I was around 26 years old. That was 6 years ago. She was 42 at the time. I was going through dark times, and I mean dark times. Prior to my relationship. I had been technically homeless. I was suppose to inherit my grandparents house but my auntie decided one day to kick me out so she could keep the house to herself. So I spent a couple days in the street, then couchsurfing at friends house and so forth. Long-story short, the woman that I'm with had a good heart and really gave me a hand in terms of making sure I had some food, just tryng to be supportive of my situation and comprehensive. She probably thought I was just a kid and just wasn't maturen enough although she never actually told me. I had lost my mother back in 2012 to colon cancer and I feel like unconsciously I saw my mom in this woman. But somewhere along the way I've done things I regret, things that made her cry. I was stupid. I cheated a couple times even though she was always there for me when I needed her. Whenever I had an appointment of some sort she'd always made sure we made it on time. That type of woman. My guilt has taken a toll on me and every time I think about it when I'm alone I drown in a guilt type of sorrow wishing I should've done better. When I get flashbacks on the day I was on my mother's deathbed I think to myself , what if I go through that again with my partner? What if I experience another loss like that? I would feel devastated and guilty af knowing that I caused emotional damage and problems. I don't know how to fix all this. I never meant to hurt her. She is doing okay I think. We avoid talking about certain things. I hope there is no hidden pain behind her smile. I hope if one day I'm gone she'll live a good life and nothing bad happens to her.