Old lover returning, advice needed

I stopped talking to this man because I found him unreliable and we didn’t want the same things. I called his number randomly today just to talk cause I didn’t think he would pick up. He did. We caught up a little and he said he wants to start talking again. He was way more polite than I’ve known him to be. He seemed like he had been wanting me back for a while. I had his number blocked for a little. He says he’s been changing and trying to mature. He sounds like it. I just stopped talking to someone very recently and wanted to take some time for myself. I told him yes, but I know he wouldn’t be mad if I changed my mind. I know what I want in a man. I just don’t know if I want one right now. Should I just tell him I want to be friends or could I be too vulnerable to be friends? Would it be ok to try again if he fixes what I disliked?