Hi Ava
I agree wholeheartedly with DL and Danielle, and with you -- that you want to make decisions that are good for you. Are you considering meeting up with him again for yourself or because you care for him and believe that he needs/wants your help and support? Don't worry about his motives behind wanting to meet, and focus instead on your own.
"...he's just doing things badly..." is excusing him, and making excuses for bad behaviour is one of the traps we fall into when we care deeply for someone who treats us badly. People won't change unless they really want to, and even then the impetus, the activity, the momentum all have to come from within themselves.
My ex only cares for things he doesn't have. He passionately pursues whatever it is that he wants, and then once he has it he's disappointed, disparaging and dismissive. When we were dating, he was truly wonderful, but when I moved in he started to emotionally pull away. I didn't have the confidence at that point (my "blinded by love" state didn't help much either) to understand that this was his problem, not mine, and to walk away... so, the first excuse. Beyond a few flashes, I didn't see that truly wonderful side of him again until I left him nearly 10 years later and he wanted me back. He's quite democratic about it all, behaving this way toward his cars, houses, jobs, pets, holidays, and even his children. He acknowledges that he does this, but says he doesn't know why and doesn't actually seem to care -- even about the emotional pain and upheaval that he creates.
Your instinct tells you that another relationship with your ex wouldn't last more that a few weeks or months, and that it would again end in you being hurt. My opinion: the debate going on in your head is from over-thinking this and letting your feelings for him cloud your feelings for yourself. Listen to your instinct and just cut him loose so that he can go find someone else to pull down and you can move forward in your own life.
Be good to yourself -- you deserve it!