Will I ever get over it or will I just keep getting insanely jealous?

I've been with my boyfriend about 5 months. He's an amazing guy. Treats me wonderfully, loves my kids, would do anything I'd ask him. We're moving in together soon and have already talked about getting married and having another kid together.

But I feel very uncomfortable with him especially when we’re intimate because all of his ex girlfriends are beautiful. I’m talking drop-dead gorgeous smokeshows. I mean, he’s cute but I thought I was dating down lol. I’m not unattractive but I’m not anything like these girls. I have some extra weight and they look like Instagram models.
I saw one on new years while we were at the bar and it triggered me big time. It honestly feels embarrassing that he was there with me when everyone knew she was his ex. So I walked out without telling anyone and refused to talk to him for 2 days. I really don’t even know why I get so triggered but it makes my physically sick to my stomach.
Like I said, he’s such an amazing guy and I literally WISH I could be that pretty or skinny or beautiful for him. Like he deserves that and I have no idea why he’s choosing me other than maybe out of obligation at this point.
How do I get over this? Will I ever get over it or will I just keep getting insanely jealous?