In a Love Triangle with Brother and Sister - Please Help

I am in love with lady i met almost 4 years ago. The problem is i got close to her family and i sometimes go out drinking with my brother-in-law. One day after a few beers, we committed the act, the sex was great both ways (giving and receivng). My brother-in-law is also married and his wife likes me a lot. He (my brother-in-law) said he loves me and i am starting to develop feelings for him. This has been going on for almost a year.

I love my woman, he loves his woman so he says - but it seem like i am falling for him and oflate: the chemistry between us is building up momentum. We are both from religious families and cannot even bring out the subject to anyone close to us and live in an African town where such topics are taboo. I seriously need help to keep my sanity. What is the best way forward.