Try to get my ex back, or just force myself to forget about her?

I think before you make that decision you have to decide what to do about the rest of your life. Otherwise you'll be back with her but still miserable and still not able to give her what she deserves. If you're not happy with your life, change it. It's just that simple. I know, as I've been there! Just matters how much you truly want to change things or how much you want to sit around and feel sorry for yourself. Commit to changing yourself for the better so you're happier, then worry about whether to get her back or not.