<human>: The other day, my brother stumbled upon a word document on my dad's computer when borrowing it for homework. He sent pictures of the document to me. Inside, was several craig's list style ads looking for men to participate in BDSM with other men. At one point in the document, it looked as if he (my dad)  had drafted a reply to one of the ads. I go to college a couple hours away from home, but my younger brother lives at home still. My dad has always been one of the most important figures in my life, and I have always had the utmost respect for him. His relationship with my mom has had its up and downs as any married couple of 20 years would have, but it seems loving overall, and I highly doubt my mom is aware of my dad's secret sexuality. 

I feel paralyzed, panicked, and utterly lost. I have no idea how to approach this, or whether to approach it at all. There's no absolute proof that he has actually gone and done anything wrong, but given what I've seen, I feel like it's likely that he has. And even if he hasn't, is it still wrong for him to be gay/bi and while married to a women who believes otherwise? Any advice is sincerely appreciated.

Can you summarize the given text in a few sentences?
<bot>: Brother found a word document containing (male on male) BDSM ads, one of which my dad had drafted reply to. Parents in committed relationship. No idea how to go forward.