My ex abused me for 12 years. We split almost 2 years ago and recently he's begun making comments to me again about how he misses me and he still masturbates over the thought of me 
Since then I was with another guy for a few months until he said he wanted kids. I cant have anymore so that ended that. But now he's sending me dick pics.
And then there's guy number 3 who when I'm in a relationship will send me dick pics
and beg to be with me but isn't interested when I'm actually single.
.I dont think I'm ugly but I'm also no supermodel.
What is it about me that makes them think they can play me like this? I've told all 3 of them to do one I'm not interested, but it doesn't seem to stop them. I've now blocked those I can but the 1st one is dad to my 3 kids. I've already blocked him on Facebook, Instagram and twitter. He only has my number.
What can I do to avoid this conundrum in future? I would like to find someone else eventually but I want someone to actually want to be with me, not someone who just likes the idea of me