I 22f am jealous of 28m male best friend

My partner 28m and I 22f have been together for only 10 months in a long distance relationship, for the majority of the relationship his best friend wasn’t in the picture as they had fallen out and it seemed my partner had no intention of reconciling with him as he was “dead to him”… fast forward several months later he’s back in the picture,which came as a shock but I tried to support and be happy that my partner had his best friend back! But now I couldn’t feel more unhappy and uncomfortable with their friendship!

My partner is sweet, respectful and loving but his best friend is the complete opposite of my boyfriend’s character! He’s rude, has no respect for his girlfriend and shares personal details of sexual acts and kinks his girlfriend performs on him to all his friends unprovoked) I don’t know if this is a normal guy thing but to me this is incredibly disrespectful) He has no respect for me or my boyfriends time together as we only see each other once a month for around 10 days, in those 10 days they are constantly messaging each other, my boyfriend moans about him messaging him but then continues to engage in conversation with him, this is something we have argued about a few times ultimately settling on the agreement that my boyfriend turns off his message notifications from him when we get to spend the 10 days together which I think is only fair as he gets 3 weeks to talk and game with him all he wants! This worked out great the next time we met up, he seemed present with me and we had fun,but now it seems to be slipping again this visit. He’s back to being on his phone, taking pictures on our trips out of things his friend likes and starts sending them in the middle of our nice day out together which then ofc leads to a conversation when it’s meant to be a day out for me and him, not me, him and his best friend! and even planning a trip to travel down to see him for a few days while we are together! It seems his friend is always in the back of his mind while we are together almost like he’s bored of just being with me for the 10 days. I feel like I’m having to compete for my boyfriend’s attention sometimes and it hurts. Like I’m in a three way relationship almost!
I don’t know why my boyfriend would want to be friends with someone like that, it makes me question my boyfriend’s character and what he talks about with him! I just see this friend as a bad influence on him.

I have jealousy issues stemming from past relationships and broken trust, I don’t know if this is causing an overreaction or if my feelings are unjust or I’m in my head! I just want some unbiased advice on if I’m justified in what I’m feeling or if I’m looking into things!

Sorry for the long read I’m not great at articulating myself!

TL;DR: I’m jealous on my boyfriend’s male best friend, are my feelings unjustified?