Forgiveness is not approval. You have to do it because it is how you let go of your resentment. I’m sure it’s quoted here on this site somewhere but it’s worth repeating: Keeping Resentment (and anger) is like you drinking poison and hoping the other person will die from it.

Hopefully you are active with your sons. Try to focus on that. Exercise or start cooking really healthy meals. If you already do then think about some other ways to make extra income. Even if it isn’t feasible now, in two years it may be if you lay the groundwork now. It will take some time but just focus on what you need to do to improve, not on your ex.