Look to the future OP
Your children will be proud of you. They sound a bit young at the moment.
You will be proud of them.
You can't change the past,. But you aren't going that way.
Who wants a "big house"?
A cosy, love filled house yes. But big is JUST big.
Your body has created two new humans. You have access to the world wide web full of knowledge and, might take a while to find them, good people. Spend your time seeking out ways to improve your health. There are thousands of people who have been through everything online who are kind enough to pass on knowledge, experience, what has worked and not worked for them, for free, online. Use their kindness.
We all get buried in the same size box OP. Try and not let what you don't have absorb your life.
Cuddle your baby, play teddy tea set with toddler? Splash in a puddle. Have a second childhood playing with your children. I did. I never had a train set as a child but I made up for that with our kids. Think I was the most upset when they outgrew it. (I put on a brave face as I handed it to their nursery school).
My H's mates are all high achievers. H took a bit longer to get going. We were much more let's see where today takes us. It took me and the kids and over a decade to get H where he is now. And the high achievers, ove half their kids are on ASD medications, the parents are stressed keeping up a lifestyle that looks from the outside hard work and shallow. Give me a more modest life and kids not on medication anyday of the week.
You have a house, good partner and two kids despite your previous marriage and childhood. You are stronger than you know. Don't let your past continue to suck joy from your future. That really would be a waste.
Wish you well OP.