I know a lot of my issues come from a past relationship where I was cheated on. A lot.

The person he cheated on me with was a "friend" he saw as a "sister or something" and I always just had a bad feeling abt her. 

Fast forward to present day, my bf now has a lot of female friends from school and his childhood. One in particular I notice he 'likes' and reacts to her selfies. She doesn't seem to like me, for no reason I can think of. I've never met her in person, just interacted through social media. 

We've gotten into fights in the past about thirst trap accounts and him liking other girls photos makes me feel insecure. I know if I told him I was upset over him liking his friends photo he'd get mad, because it's "only his childhood friend" but I can't help this feeling of despair well up in my chest. 

Any advice?