That's something, unfortunately, I've heard a lot from girls dating Greek men. It's not fair but she will cause you such grief and in the long run.....he'll give in to his mother and family pressures. Not all Greek men are like that, but in my experience, Greek men are mama's boys. (Sorry , Greek men who aren't !) Also, it does depend on a few factors; Is she mean-spirited ? Will he stand up to her ? Tell him your concerns. Unfort., you and if you marry him, your husband are not islands, you'll want the feeliing of family....going to family affairs. Sometimes I've seen when you do have children and the mother-in-law is hateful, the childtren suffer. So there's a lot of factors here.
Don't let her get between y'all. If you break up with him, she gets what she wants. If he makes you happy and y'all love each other, don't let anyone come in between you two. It's going to be y'all two for the rest of your lives as husband and wife. Don't let her get to you. Being a single mom proves your a strong woman. Best of luck darlin.