Liked Someone I Shouldn't Like

I need some advice... My mother said a few days ago she and my dad are in a open relationship, and it's been like this for a year now, I realized they weren't seeing each other that much and they stopped sleeping together... She even told me she was seeing other guys... How should I feel about this..? I've been acting like everything is fine, but I'm scared... I'm scared they may just divorce... They even said if they found someone new, they would instantly divorce each other... I still continued smiling, but I haven't been sleeping well, and I keep thinking about it, mangago is the only thing that could actually keep me smiling... I love everyone here, so please, tell me what should I do? I don't know what to say, how should I feel? Is this okay to continue things like this? I've been getting mixed emotions ever since I heard about that. She even openly talks about the people she hooks up with and say how other men look hot, my heart stings, but I know my dad is doing the same thing, he is also seeing other women... And my mom is going out to more clubs, she even say how the men there looks amazing and how she is hooking up with one of the guys there. I'm slowly losing my mind about this, i'm just.. So.. So, scared.