I don't like my boyfriend's best friend but I don't want to be controlling

[idkdude]

I've been dating a guy for a month (we're gay, just to avoid confusion). He has a best friend that he met during orientation and admittedly had a crush on when they first met. His friend is super attractive and lots of people have crushes on him (he's also bisexual). He's also really messy with his relationships and has been involved in a bunch of love triangles and hookups in the few months we've been in college.
I have severe social anxiety, so I thought I was just being weird around his friend because he intimidated me, but the more I see them together, the more jealous I get. My boyfriend is really touchy with him and sometimes holds hands with him. He has a heart emoji next to him in his phone, even before he had one for me (not that that's a big thing lol but it was just weird to me). They always make sexual jokes at each other and put their arms around each other. My bf has nipple piercings and the other day his friend was literally touching his nipples through his shirt in public. His whole friend group is weird and overly-sexual with each other, so I can't tell if it's a normal thing for them to do and I try not to get mad about it.
My boyfriend can tell that I don't like his buddy because I try to avoid hanging out with them when they're together because it makes me so uncomfortable. My boyfriend asked about it and I've openly expressed that I feel jealous of him. He reassures me that the crush was really short-lived and he sees him as a brother but I can't shake the feeling that they like each other.
Even though I know I'm not the most attractive person on the planet, I'm usually really comfortable with the way I look, but comparing myself to someone super hot and desirable is taking a really bad toll on my self-esteem. This guy is literally just as good at everything I'm good at, if not better.
Today at lunch, one of our mutual friends told us that a friend of theirs thought my boyfriend was dating his best friend and I can see why. I thought they were into each other when I first met him.
I know I can get irrationally jealous sometimes and I really really don't want to be controlling or abusive, but I just want my boyfriend to chill out with the touchiness. It's really uncomfortable seeing him look like he's flirting with someone else in front of me. I don't want him to stop seeing his friends because of me and I want him to be himself and act however he wants. How can I solve this problem without being abusive?