Am I crazy for being scared?

Trish
Recently my ex boyfriend and I got back into contact with each other. I was the one who made the first contact because I wanted to see how he was. I heard stories from shared friends that he was struggling with nursing school and he failed one of his courses. The curious person I am, I decided to see what would happen if I reached out to him. He replied back and from that day on we slowly started talking again. It's been almost 2 years since we last talked with each other. Instead of just talking to him directly about unresolved issues I decided to play it maturely and take my time to make him feel comfortable opening up to me. I would invite him to hang out with our shared group of friends and we would have random hangouts with other people. For two weeks we never went out alone (just the two of us). Then one day we decided to have lunch together and just talk. So a little background on our breakup, it was not good (which is the case for many breakups). It ended pretty bad because of so many situations that went wrong. Anyways, our lunch hangout went well. We brought up some unresolved issues and he ended up apologizing for a lot of things, i.e how he handled the breakup. We ended up noticing that we still had strong feelings for each other. We still care so much about each other and so we are slowly working things out. Trying to keep communication open and building a stronger foundation for us to start on. We haven't made anything official (BF and GF) . But we are acting as if we are. We talk to each other like we're together and we hold hands/link arms when we're in public. We go on dates and do normal couple stuff. We are sexually active with each other too. We're just scared to put a label on it, especially me since he was the one who broke it off. Before this gets super long I just want to ask am I crazy for feeling scared that things aren't going to work out? I'm always feeling like I'm being delusional that things will be better the second time around. If there's anyone else whose had experience with something like this I would like to hear your story. Or if there's any advice from anyone I would definitely like to hear it.