Husband [27M] needs specific kind of sex or he’s leaving

My husband [27M] and I [27F] have been married for almost 5 years. We have two young children (3mo F and 15mo M). We have been talking over the past few nights about our relationship and sexual needs. Our sex life has been up and down over the past few years due to being pregnant and the limitations after childbirth. There has also been some sexual infidelity on his end a few times. I stayed with him because I love our family and our life together overall and for me personally, it’s just not a bad enough reason to leave.

In our talks following his most recent infidelity, he revealed last night that anal sex is a deal breaker for him, and if I’m not willing to do it 2x per week with him, he does not want to remain married out of fear he will get continue to get his sexual needs filled elsewhere. I do not like anal, it is painful at worst and uncomfortable at best, but never pleasurable. It kills my entire mood if we are having vaginal sex and he wants to transition to anal.

Am I being unreasonable for not wanting to agree to anal 2x per week (we have vaginal or oral sex 3x per week)? I feel like it is selfish of him to break up our family and the life we’ve known the past 5 years over something like this. It’s not like we don’t have sex, he just wants more than I’m comfortable giving him and he feels it’s worth losing his family over. I’m at a loss. Please give me new perspectives or any advice you have.