Wow...I feel like I'm reading one of my old posts from a little over a year ago. My ex was the same way. Him and his girlfriend had been together for a few years and when we got together, they were still friends. She would openly text him saying how much she missed him etc... Finally it did break us up. Not just that reason, there were others, but I wasn't ready to deal with that - still very jealous at the time.

So after we broke up I was just waiting for them to get back together but here, over a year later, they still aren't. I have seen him a few times and flat out said "we're not together, we won't be together so there is no reason to lie anymore - did you ever have feelings for her when we were together?" and he said absolutely no. He claimed he still had feelings for me. So I truly believe that they really were just friends and I figured....if he didn't want to be with me, he wouldn't have.

Also, she refused to come around me because she still wanted him. We NEVER hung out together. I think the fact that he brings her around you and she is nice to you and wants to hang out with both of you that is a good sign. It sounds like, even if she still does have feelings for him, she doesn't sound like she would disrespect the boundaries of your relationship.

The sneaking up on someone and tickling almost sounds more sibling to me than flirting. My brother tries to scare the crap out of me on a daily basis lol. It sounds like he cares about you - at least he's not lying about her or sneaking around with her.

I would just explain that some of the things they do upset you. If he gets upset and yells or gets on the defensive there might be something else but if he seems understanding and supports you and tries to make you feel better....that's the kind of response you want. Just go to him; holding it in until it bursts out in a fit of psycho girlfriend rage isn't the way to go (trust me haha).