HELP... my stepkids mom hates me?

Please, I am a stepmom of two and I love them dearly and they do too. Their mom hates me and makes my life miserable. Any chance she has to stir up problems she'll take it. My kids always tell me all the mean things she tells them about me. My hubby tells me to ignore her and not give her any importance but enough is enough. She tries to intimidate me but I am tire of her, what can I do?? My mom tells me living well is the best revenge...is this true. Is she jealous of me for her kids or my husband? Please help me, your opinion will really help me. THANK U