Hmm, I'm not sure what you could do. You say your number is blocked, is there anyway you can proove that right there on the spot? So your dad can see? By how you feel about her, I'm wondering why your dad is together with her :/ She doesn't sound like a good wife.

Being the bigger person, if the other one can't, is usually the best thing you can do, and thinking like: I'm here for such a short time, is it really worth to start making huge fights? But on the other hand, maybe if it can be discussed finally, it can do some good?