SIL always making underhanded comments

As long as I can remember she never liked me being with her brother she went as far to say he was cheating on me and say it was with her friends and has tried to break us up many times I have always tried to get along with her but she called me derogatory nick names and is generally callous with me, she also has problems with her fertility because of her HBP and type 2 diabetes so every time I’ve gotten pregnant she has taken it badly and made comments about my children saying they look like aliens or drowned rats 😒 now that I’m pregnant again ,she’s making worse comments and her brother won’t say anything because he says she is joking and not serious but it doesn’t seem like that all I can do is stay away from her and not allow her to be around my children since she can’t respect me, but my partner doesn’t stand their ground.