Glad you are going to a meeting and that your mom is going,too.
Please don't count on your dad decided to get help just because your mom leaves or asks him to leave. Sometimes it happens;sometimes not. ( in my case my husband decided to continue drinking over our 27yr marriage and our two children.....at least so far) Doing what is best for YOU is always a good choice,no matter what he decides.
Let us know how the meeting goes!