Sexually explicit jokes / comments?

My boyfriend of a bit more than a year has female friends. Lots of them, who he speaks to frequently via text and IM. In these conversations, though I've been very clear about how uncomfortable I am with it, he makes very explicit "jokes" and comments to these girls. Last nights example was a quote from a comedy skit; "can I dip it in your a@$?", but there are other times where it's just a direct inappropriate comment of similar explicitness regarding them, a sexual scenario, a suggestion that he do something perverted, etc. His take on this is that he has the right to have his sense of humor, and that considering I have an exqually twisted sense of humor, it has to be okay that he can speak this way to other girls. His example was to ask if I had ever used the tried and true quip, "that's what she said", and if so, if violated my own rules and was creating a double standard. Now, while I have to admit I have dropped a "that's what she said", I have very, very few guys that I speak to with any regularity, none of which i would be comfortable saying something like he says in his conversations with girls. Additionally, I feel that jokes along the lines of what he said are in altogether different category than a joke used in a show like The Office. Also, considering we have both have had fidelity problems in our relationship, including very straightforward inappropriate texting with people of the opposite sex, I feel it's even more reasonable to ask for firm boundaries that include not considering your natural sense of humor as a right to speak that way to friends of the opposite sex in that way. If I had my way, close or private friendships with member of the opposite sex would be reasonably stopped until trust in the relationship fidelity had been rebuilt, if possible. Since I have a strong opinion that I am in the right, as does he, I'd like to get the views of others in relationships who have experienced something similar. My trust issues are definitely a problem, but they are really hard to address, in my mind, when this behavior is the definition of inappropriate and why I feel my trust is constantly aggravated. When he disregards my feelings and does this anyway, I also feel disregarded and like my relationship is secondary to him behaving in whatever manner he alone deems appropriate. I'm definitely unhappy, and perhaps need to be told either that I'm unreasonable and need to get a grip, or told that I'm justified in my expectations so I can strengthen my resolve to move out of something I'm unhappy in. Much appreciation in advance.

I've hung with the same crowd since high school, (a large group of people), and have dated a few of them. I've gotten a few comments at parties regarding sex from guys but nothing like your talking about. This guy sounds mean.