His ex-fiancé is still on his phone plan...?

Yeah, I'm the new girlfriend. "New." It's been like a year. But compared to his EX... Whatever. They dated a year and were engaged for a year and he called it off. He was barely seventeen, and she's like nineteen or twenty and that was crazy. She is still convinced she will marry him. And she was on his phone plan... And still is. Every month she comes into his house and chats up his mom. Like they are old pals. The reason he called it off is because his mother talked some sense into him. It was a horrible relationship and his ex is awful and his mom despises her. I'm the only girlfriend she's ever liked. We have great relationships with eachother's families. (he still lives with his parents & me too, he's now eighteen I'm seventeen) his ex fiancé comes "to pay the phone bill" and I know she does but it always seems like... More. I know for a fact, the week after he asked me out, he slept with her again but he fessed up and cried and he worked for months to keep me, and we have a great relationship now and trust is rebuilt for the most part... But last night, me and him were on the couch in his house and she came by to pay the phone bill- and his wonderful mom made it so she didn't make it out of the front room, and I just had to hear her nails-on-a- chalkboard voice. MY boyfriend... Her ex-fiancé... Was completely drugged because he had his wisdom teeth removed, and his mom and I were taking turns taking care of him. But I am leaving for Christmas and we won't see eachother for weeks. I'm really scared his ex will take advantage of this and... You know... I'm scared. And I hate that she's on the phone bill but it costs a lot to switch before the contract is up. How do I handle this? I want to talk to him about it but I have to go over and take care of him again today, he is still drugged and his face is puffy and he is in a lot of pain. I leave Thursday and I won't be on this continent. What do I do? It's killing me.