I think my Mom is having an affair.. Advuice?

I was suspicious when she started having mysterious phone calls at night. So being nosey I went onto her myspace and I clicked a guy and he had pictures of her and it said that he loves her and she had left comments saying she loves him. Now I'm worried, yet I'm angry because of what she's doing. She's ruining my life, my dad's and my brother's. Maybe even hers. I feel that I will never talk to her again if she is doing what I think..