Basically there was a guy who I worked with for about 8 months, he was slightly newer than me although a lot older and was going through some of the same issues I was when he joined. I seemed to be one of few people he felt comfortable talking to and I felt sorry for him so I tried to help as best I could, give advice etc. We worked on different teams and I didn't see him that much so it wasn't a massive inconvenience and I consider myself to be a decent, empathetic person who tries to help people.
Anyway, I won't go into all the details but he had a lot of problems with doing the job and squabbling with colleagues so he left before he was forced out of the organisation.
It wasn't immediately obvious to me at first but some colleagues did warn me he probably fancied me even though he never said anything inappropriate to me.
Ever since he got my number (many colleagues have my number although I really wish I'd never given him mine as I didn't expect the constant communication) he messages me on a near-daily basis, sometimes I receive several messages per day from him. Most of the time I don't respond, not just because I find the level of contact inappropriate for someone who was an ex-colleague, someone I wouldn't even call a friend, but because I'm busy also working long hours and living my own life, dealing with my own problems.
Again, he hasn't said anything inappropriate or ever commented on my appearance but the level of contact itself feels like he wants something more and I find it odd that when I don't reply he just basically has a one-way conversation with himself on the chat facility he messages me on, just posting random inane stuff I don't care about.
Because he is currently unemployed and has talked about having depression I feel bad blocking him but I honestly don't know how much more I can put up with this. I avoid speaking to my friends on this app now because whenever he sees I'm online he sees that as an invitation to bombard me with messages. It's a weird feeling but I almost feel really oppressed by his demands for my time and attention.
Any advice please? I've tried to be subtle but gently firm before saying I'm busy or posting minimal word replies but then a few days later it all starts again.