I don't know if I'm being unreasonable, over sensitive or if this is how others would feel. DP told me that he has been invited over by his ex to celebrate their DC's birthday, they are an older teen so will be a 'family' dinner. He was hesitant about telling as he knew it would upset me and of course he wants to see his DC on their birthday but I feel like I am being excluded. His ex has been dismissive about me and acts in a passive aggressive manner when we have met although I was nothing to do with their break up and I have a good relationship with their DC. I trust DP and don't think there is any chance of them getting back together but I just find this a bit odd...