I married a lesbian to hide an affair with my sister

My sister and I started having ** back in 2005 when we were 15. As best I can recall it started when we had to share a room when our house was being worked on. Her room was part of the remodel so we shared the same room and bed. She was 10 months younger than me, but we were both 15. I often slept ** and K just in her underwear. One night I woke up hard against her and it just led to us making out and having ** for the first time. We never said anything to each other about it and continued having ** for a few months before we finally addressed that what we were doing wasn't normal and we had fallen romantically in love with each other.
Somehow, and for the life of me I still have no clue how they never caught us; our parents never knew. We were a bit paranoid and did all we could to hide our relationship. Thankfully K never got pregnant, and we wore condoms early on (just not for those first three months).
When we turned 18, we had graduated from high school and moved into a small apartment together on the West Coast for college. I got a vasectomy the first semester of school and we were finally free and had ** quite regularly (almost daily) and were able to share our affection more publicly/openly with some of our closest friends.
Our best friend, J, was lesbian and knew of our relationship quite well but never judged us for it. K wanted to explore her sexuality and discovered she was bi through J. J was the only person either of us have ever had ** with other than each other. J was through and through lesbian but let me have ** with her during a few threesomes back then (and very, very occasionally now). I thought either K or I would be jealous, but I often found myself more aroused watching J and K together.
A few years after college our parents became suspicious of my sister and I when they saw us holding hands one time and us cuddling another time. We were both scared. Around this time, J was trying to be in her parents' good graces as they wanted her to marry a man since they knew she was openly lesbian. J, K, and I concocted a plan to stop our parents' suspicions. I married J in 2017. That was the only time I ever had ** with J alone as K didn't come along the honeymoon. K said it was the only time she was ever jealous, and it broke both our hearts we couldn't marry. It was not something I honestly would have done, but it was worth it so K and I could continue our relationship. We count ourselves lucky. J is a great friend to myself and K and a great lover to K. Even though it is still a secret we wouldn't change a thing.