I need advice.

Typically, ex's don't apologize. Mine did. His girlfriend cheated on him and I guess he felt bad for how he treated me in the past (I was the only gf who never cheated on him.) We recently reconnected and have been talking but he has stopped texting me first and now I'm the one inviting him to do things. I won't have sex with him because 1. I'm not a rebound and 2. I will get attached and I don't want that to happen considering I still have hard feelings for him. All in all, I get crazy anxiety always afraid something bad is going to happen. I want it to work out if that is what fait decides but I'm not sure if that's what's even happening. I feel like if it was meant to be I wouldn't be getting so much anxiety over this. I can't figure out if he just wants to use me? If he is just confused? Or if he actually is interested. What do y'all think is going on, I just can't read this situation.