I accidentally overheard my mom talking to a guy she’s cheating with

She had no idea I was home and I heard her talking to guy shes cheating with

and I heard her talking very affectionately and even planning a date

My dad is currently away on a business trip, and I feel really confused and upset

The thing is, this isn’t the first time My mom has cheated multiple times before, and she also struggles with alcoholic Sometimes she doesn’t come home for days or even months cus of other men

My dad always tries to be patient and sacrifices a lot for her

I also have a 12 years old younger sister and I’m worried about her too

Should I tell my dad? Or should I talk to someone else first? Im confused