She Came Out

So me and my girlfriend have been together for a little over a month now. She just told her mom she liked girls and had a girlfriend. Her mom freaked out and said she wasn't aloud to talk to me anymore. Yet she still does secretly. Her mom constantly checks her phone, and when she finds out she hasn't listened, she gets yell at more and more. I'm 17 and she's 15. We both feel we are deeply in love with each other, but she lives in Canada and I live in the U.S..
Since we have talked on the phone and long distance calls charge, they charged my girlfriend and she was $3000 over her phone bill. I've offered to help but I doubt they use American money in Canada. So she said she would work, she's been doing it since she was 8 so she doesn't see how that'd be a problem. So I just went along with it. Finally it got to a point where her mom wants to call me and "see what's so special about Deborah".. But I'm nervous. This is going to be the first time I ever meet a girlfriends mom.. She says to be myself and I said that won't be a problem. Just one thing is on my mind.. I read a story that I was able to relate to. Where a girl had to sneak behind her parents back she eventually got tired of it and stopped talking to her partner. I don't want that to happen at all. So I'm just wondering what should I do...? Advice please <3