Am I wrong to be insecure?

My boyfriend’s kind of coming to terms with being interested in men, although he’s not much for acknowledging it because we’re in a relationship so it’s not like he needs to go out of his way to tell everyone he likes both. I swing both ways as well so that in itself doesn’t bug me at all. However, awhile back he admitted to me that he likes anal play on himself, which is basically the one thing I’m seriously uncomfortable with doing in bed. Every once in awhile he brings up doing it to himself despite knowing that I’m not into it, even that it stresses me out. The reason for the stress is that I tend to worry he’ll leave me for someone who will do for him what I can’t/won’t, i.e. something like this. It’s a peculiar thing because of course I like girls as well so it seems hypocritical, but a girl generally can’t do anything for me that a boy can’t, whereas it isn’t the same the other way around. Am I crazy for being insecure about it? Is he wrong to bring it up knowing it upsets me/makes me uncomfortable?? Have any of you had similar experiences, and if so how did you handle them?