I've been carrying my failures, with me for a long time. I think looking at them is a good step. You have to realize that at the time you made the ''mistakes'' you did what you knew then, how to do. You did your best with what you knew and your circumstances at the time.
I tell myself this. I have had ''mother's guilt'', constantly beating myself up for what I think was a mistake. I know, looking back at it where my mistakes were, but I can't change anything. All I can do is the best I can do every day. If you're able to access youtube, there are people coming from all walks of life that will talk about things like this. One new channel I watched is called ''The functional melancholic''... basically he says the world has taught us wrong. Spending time in school learning some things we will never use in life.
That's only one part of it. It's basically saying that reality is harsh, but learning ways to cope with what you have now, and maybe learning new things, such as building or painting or drawing something that only you can make. Only you know how the world looks to you, no one else can see it through your eyes. I'm sure there's talent there, and you've been helpful on this forum, you are welcomed here.
If you could start by doing one thing you can afford to do, and make it a hobby, maybe that would help you focus less on the negatives of life.