My fiancee's mother hates me with a burning passion?

She says I'm stealing both of her men from her (her husband and oldest son) because her husband always invites me to sporting events because I like sports and it's not like she doesn't have other sons she has 4 more but she said that she's going to break us up and I want to call her a ***** and kick her *** so hard but I don't want to lose him because of her what should I do