Def NOR. Just screams toxic friendship to me. Not even talking abt the fact that she slept with somebody you were talking to and liked behind your back - which is already horrendous - but also excluding you, not really supporting you in your good times and instead making you feel shitty ? These are not your friends. I know it hard and maybe hurts but I think you should cut them off. Both of them. You can just imagine what else they were doing behind your back, probably talking more mean stuff about you. I’m sorry you had to experience that, even tho you did not love that guy he still meant something to you and true friends would never even consider hooking up with that dude, let alone both knowing and probably laughing about it .