4 months LTR met a guy, went out to movies and to eat with him alone.

I told her I don’t like it when she goes out one on one with another guy. She says it’s her fault and says won’t happen again. She claims that they’re just friends.

She has been texting him a lot. Exchanging some selfies, etc. I’ve noticed less affection and attention from her since then.

I said some insecure stuff and asked if she doesn’t like me anymore or something. I went through their messages in front of her, she says I don’t trust her. Claims again that they’re friends.

Spent some time this Saturday with her.

Then I just broke up with her over the phone.

Is that the right course of action?