<human>: Hey guys, so I have been really conflicted lately. Our friend group has been together for quite some time now, and my little brother has been getting closer and closer to the female friend in the group for some time now.

I believe it started last October with some late night conversations where he would ask relationship advice or just have someone to vent to, which is fine we all have to have that one person. 

But in Febuary I found something. My brother was having hard drive trouble and he asked me to take a look at it. While rooting around for the issue I found these videos of Skype calls. It was almost every conversation that they have ever had. I was immediately concerned. I did the right thing and confronted him and let her know what was going on. She seemed distressed and was going to talk to him about it. I thought it would alright from there on out but I was wrong.

It turns out I might have awoken something between the two of them. She has even gone as far as to make an alternate Skype account. I am sure they have been using snapchat too.

Am I being to invasive? I am pretty sure it's illegal because he is 17. Do I tell her boyfriend? Do I confront them again? Do I just let them have their fun and just ignore it?

Can you provide a brief overview of the text?
<bot>: I am sure that my brother and our friend are having an affair. She has a boyfriend and my brother is underage. What steps should I take next?