Reaching out after I messed up?

Trying to make a long story short, so feel free to ask for more details, that's fine. I (30s, F) met and dated a guy (30s, M) about a year ago. We only dated for a couple of months. I kind of got in my head about some things, and wound up breaking it off. But I had liked him, and I wish I had done things differently. I was recently thinking about getting back in touch with him, but I wanted opinions and if you think reaching out is a good idea, what would make for a good check in text.