<human>: Can you summarize the given text in a few sentences?

I've been in a number of horrible relationships with people where I have been betrayed a numerous amount of times. I am having issues with feelings of extreme anger and betrayal popping up in situations I feel may be ordinary. For example, a few days ago my friend mentioned how he was excited to get to go to a rock climbing event hosted by a new club that was offering it for free to people over the age of 21. He mentioned that they were looking to bring as many people as possible to promote their club. After hearing that I kind of assumed I would be invited (maybe that is my mistake?) and expressed interest in it and said how it sounded like an awesome experience. He ends up not saying anything about it and not inviting me which is fine, but then later he brings up he and my friend went together. This really bothers me. I don't understand why it is viewed as okay to talk about cool things you go and do with other people in front of them if you aren't going to invite them. Especially after saying how it was free for anyone to come to which implies that I could have been invited. I haven't said anything about how it bothers me yet as I'm not sure if I'm just over reacting and this is a normal thing to have happen, but I am super super upset about it. Should I be?

I have had similar issues with this group of friends in the past where a lot of them gossip behind each others backs and will talk about what cool things they are doing later and not invite me. I was under the impression that this sort of disrespectful behavior only happened in high school but I am becoming increasingly fearful that will not be the case. Is this something I'm going to have to live with forever? Is this something everyone puts up with in all friend groups but because they don't get as angry as I do and it is bearable?
<bot>: My friend talked about a cool event which they could have invited me to but didn't which left me feeling extremely angry. Is this an over the top reaction?