Closeted bi coming out, really want a m/m experience. Where is safe and no strings attached?

Hi r/gay. Deep down I've always known I'm bi, but lately in my internet browsing have come to accept/embrace it. I'd love to explore it a bit, bit I'm in a long term m/f relationship and have a little one too. Any advice on how to explore this a bit? I don't want to use grindr or similar because my phone isn't always in my hands, would prefer an email type deal. Any suggestions?