So my ex boyfriend has been emailing me (letters included) is he interested again? Kinda long..?

To me, it sounds like you both still like and have feelings for each other. You are thinking back on your decisions of why you broke up in the first place and hearing from your ex is a bit exciting especially if you haven't completely moved on (assuming you're not dating anyone) and he hasn't moved on either. You two are on the same page right now. I'm not sure if getting back together is the right thing to do (although he did say he doesn't wanna get back with you...I feel that he wants to be at least a part of your life) because maybe you two still have feelings for each because you have not found someone new to like or date. But maybe it is the right thing to do because you realize your life is better with him. If you feel like the positives of seeing him outweigh the negatives, just have lunch and meet up. You both clearly miss each other..maybe not on gf/bf level, but at least friendship wise.