Insecurity Around Threesomes...

This has been an ongoing issue for me in my relationship for a year and a half now. It’s driving me insane and I just need ANY advice on how to stop myself from reacting this way.

My boyfriend and I are 20 and have been together a little over 3 years now. In January 2019 we were going through quite a bit and one of the biggest issues I had was this constant pressure to have a threesome. It destroyed my self esteem and made me resent him so much...in April 2019 we broke up for a month.

We’ve been back together for over a year now and I let him know how much he hurt me and he’s never brought it up since. However, that period of time has affected me so much.

We’ll watch a movie with a threesome scene and I’ll try so so hard not to react, but I just involuntarily start crying. It’s gotten a little better, if I don’t cry I become a little cold. I just feel so inadequate and although he doesn’t bring it up I know from that time period how badly he wants it.

I am very close with his older brother and his fiancé, she and I tell each other everything. She’s 25, so a lot older and more mature. She told me she had big news to tell me, my BF and I were brainstorming and thought maybe she was pregnant. She said she and him had a threesome over the weekend. Of course, our relationships are different and I’m not judging what they do but it just made me feel so horrible.

I told my boyfriend “oh she’s not pregnant btw” and he asked what it was and I said “nothing, don’t worry” but I think he could tell what it was and I was upset.

I just feel like such a failure, why can’t I be adventurous? Why can’t I just want to have a threesome? What’s wrong with me? I just feel so inadequate and not enough.