He won't let me move on?

My ex and I had a passionate and strong relationship for about a year.
He went away to uni and decided he would rather be single and get around.
We are civil with each other, tried being friends but it wasn't working out so cut off contact about a month or so ago.
We have been broken up for about 3 months now and he is seeing/sleeping with a mutual friend of ours.
He occasionally tags me in Facebook things and has been liking pretty much every picture I put on Facebook. ANd then a few hours later she will like everything he likes go mine.
I don't want to block either of them because I want to keep it civil and we all have mutual friends and things.
It's really getting to me because I am still in love with him and finding it hard to move on, this isn't helping.

I am also going to see them together this weekend at a party.
He won't let me move on?
Add Opinion