My son is marrying a Protestant heretic!?

We are a Greek family, so my children were raised in the Orthodox Church. My son has come of age and is now engaged, but he's engaged to a protestant! I don't know what to do about this. I always hoped he'd find a nice greek girl, or maybe a russian or serbian. A Catholic at the very least since both the Catholic and Orthodox Churches are of Apostolic origins, while Protestant churches were founded fairly recently by random people. But anyways, he's now instead with some tambourine shaking baptist! I just don't want her to start bringing him to that fake church of her's and him end up going to hell. How can I fix this?