Am I overreacting? ~ Need advice!

My boyfriend of 3.5 years broke up with me because he was getting bored and was jealous of his single friends, he said he missed chasing girls. I was totally in love with him and so this really destroyed me, I know he didn't cheat but my confidence and self esteem was ruined.

About a month later, he sent me loads of messages saying how stupid he had been and how he missed me and wanted to get back together and that he'd do anything to get me back. We almost immediately got back together.

Hes now saying that he's going on holiday with a group of his friends to one of those party countries where people go to drink, do drugs and have one night stands. He's going with mainly single people and the one person that's in a relationship has cheated on his gf before. This just reminds me of what he said when he broke up with me.

Usually I wouldn't mind him going on holiday but I'm so insecure after what he said to me and really don't want him to go, am I being controlling? I don't want to be a crazy girlfriend I'm just hurt by this.

Any help would be really appreciated <3