I don't necessarily want to argue your parenting. I don't think anyone is going to change your mind at this point in time as you really seem to be on a kick about it right now BUT here's another view point. Let's say you actually were a shitty parent, which is still up for discussion, but whatever... what're you gonna do? Kill yourself over it? Is that going to make it better for them? No, you're going to fuck those kids up more than they are now. So get it together and amend the relationships you're having with the kids now rather than beating yourself up over what may or may not be. Children need their parents, whether they are 2 years old or 22 or 62. Those relationships change over time and sometimes kids don't think they need the parents and go for periods without talking to them much, like when they're trying to get their feet off the ground in their 20's.
I don't know how old your kids are but they need their mom. And they will in the future too, even if they're acting like shits right now.
Furthermore, my mother killed herself when I was 25. That was more than 15 years ago now and believe me, I wasn't at a great age. I didn't call. I didn't show up at her house. But in retrospect I couldn't used some more mom time. She missed a lot of stuff. She missed my nephew being born, she missed graduations, she missed me getting married... I could go on but the point is I wasn't done with my mom even though I was an asshole. And your kids aren't done with you even though they may be assholes or you may have been in the past. Move on. It's time to stop beating yourself up over the past.
P.S. Understand that I mean all this in the best way. You know I dig you. ((hugs))