My fiancé just told me he’s bisexual

I’ve been engaged for 6 months and my fiancé just told me he’s bi-sexual and I don’t know how I feel about it. He confessed that he’s had sexual encounters with men while we were broken up 2 years ago. He says he has no interest in being in a relationship with a guy but sees having sex with one as “kinky and taboo”. We’re supposed to be getting married in June and he drops this on me two weeks before half of our deposit is due for our wedding venue. He claims he felt like it was fair for me to know who he really is. Idk how I feel about it, I’m lost and honestly it does make sense to me. What should I do?