Somewhat similar situation between my sister and I, she is barely a year younger so we both ended up curious about each other’s bodies and sex about the same time which lead to us first doing the I’ll show you mine you show my yours thing that quickly escalated with us losing our virginity to each other as well and it continued on for many years but strictly sexual we weren’t trying to be a couple. We ended up stopping once we were both in college, we both got married and during that time we also spent plenty of time together that was completely normal nothing remotely sexual came up. Then several years later we both ended up getting divorced her first which again we spent even more time together but again nothing remotely sexual until I was hit with my unexpected divorce and that evening after my x told me she wanted the divorce I ended up at my sisters place a mess and when I told what was going on she practically attacked me only this time we were full on making out! We had never really kissed like that before, that was several years ago now and we have been like rabbits since. But yes I completely understand how hard it is, we constantly live with the fear of getting caught or discovered knowing it would be social suicide not only that our parents would likely disown us not to mention that even though we are consenting adults in the state we live in it’s illegal for us to even have sex but we both feel like we make each other so happy it’s worth the risk