Am I wrong for feeling so uncomfortable at his messages (details inside)

The guy in question is a former middle school classmate of mine. He had an undiagnosed mental problem that rendered his mental age much younger than his peers. He had a crush on me back in the day. I don’t know about his mental condition at the moment, but it seems that he is doing well.

A couple of weeks ago he found me on FB and messaged me. He asked how I was doing. I replied and he started asking things like what job I’m doing and where my workplace is. He just kept on asking these short questions. I stopped replying when he asked if I have got married because I was just feeling exhausted of answering his questions.

A few minutes ago he sent me a message wishing me a good Women’s day. I said thanks and he immediately went back to the question of whether I got married. I said no and he asked how my brother is doing. I still haven’t replied to him yet because I just feel so uncomfortable.

I get it, he is trying to be nice by being interested in me, and he means no harm at all. But I just can’t help feeling so uncomfortable at his questions. Why do I feel this way over his messages?