MOMS HELP ME THERE IS A CHILD IN NEED

Im 15 and my mom is cheating never coming home on the weekends and everyday she doesn't come home it hurts my heart.What she is doing affects me so much but she is too selfish to understand that.There is no justifying cheating.But things have gotten worse.she now is only home 3 days out of the week.My dad is home and he knows its happening and it hurts him so much.(he isn't the greatest dad or companion but no one deserves to feel this way)soon he will be gone and I will have no one.She is going to continue leaving everyday to see this guy and it doesn't matter if I tell her how I feel.

My mom is ashamed of me and has broken my heart.the more she does this I can't look at her or speak to her.if I do I'm going to make her cry.Moms I need comfort and support please give advice.I just need a parent for a second....