Another Facebook predator?!

A perplexing situation:

My high school geography teacher is on my Facebook page. I haven't seen him in 20 years, and we didn't talk much back then. He's almost 70, probably extremely lonely.

Anyway. He has been liking just about every facebook post and picture I put up, says we have heaps in common. I've been a bit morbid on there lately because my brother's fiance has just died of cancer. He tells me I'm depressed, gives me his number, and private messages me to talk!!!!

I just said I'm not depressed, just sad because of a death in the family. He kept the convo going about other cancer deaths in his family, but I'd backed off fully by then.

Red Flags Are Flying!!!!!

Either he is a compulsive caregiver (codependent) or he is an abuser.
Either way, he has probably fallen in love with my facebook image and that is Not OK with me. He is over 30 years older!

Am I right to get the heebee jeebees about this situation, are my instincts protecting me.
What am I doing wrong on facebook to attract this situation into my life.