I think it is often useful to try to understand our past, but it is also important to accept that we did what we did back then usually with good intentions deep down. Often we made decisions when we were naive and maybe vulnerable. We need to be forgiving and kind towards the person we were during all our yesterdays.
The past is now one of those things we cannot change (as in the Serenity Prayer). Today and the future are what we can influence with the wisdom we have now gained.
Today you have your children in all their variety and with all their complications and difficulties. They need to live, as you do, in this day and all their future days. Try not to spend your precious energy on the ‘wrong’ choices of the past. I know that is not an easy task, when you are questioning your life and feeling in some way ‘to blame’ for its problems. As you know and understand yourself more, let this lead to loving and accepting yourself more fully , too.
Just some thoughts from reading your post – I hope they make sense.