Stepkids turned against me!

My step kids mom hates me. She is doing everything in her power to make sure the kids know that I am not their real mother and that they disrespect me. They are only babies, but are in the stage where they repeat what they hear. My stepson has started saying "bitch" and runs from me likes he scared. My husband and I have been together for a year, and the kids come over every single weekend, so I feel like by now they should be used to me. Every opportunity the kids mother gets to communicate with me..its always negative. To her I'm a bitch, whore, will never take her place, etc. Keep in mind that I'm not trying to compete with her. Never was, nor am I trying to take her place as their mother. But I do feel like I should be respected. I take better care of her kids than she does. She doesn't bathe the kids daily. Every time we get them, they have a new rash somewhere. Her grandma has called my husband multiple times b/c after visiting her and the kids, she said the kids would run up to her crying about how hungry they are and when she's confronted she says she doesn't care and throws them a bag of chips to shut them up (is what we were told from her grandma) When They are with us they eat properly, I help buy the things they need, and even sent his daughter back home with some of my daughter's old clothes. Yet, I'm still called out my name and bashed. She has her family harassing me saying I'm a homewrecker. When my husband and I first started dating, they had broken up. She was laughing about their breakup, posting all over fb, saying he was just one of his phases. I guess she thought him being mad was funny b/c she thought that maybe he would come running bk after he cooled down or that they argued so much that she thought it was just another little petty fight??? Idk what her reasons were, but little did she know..he had already made up in his mind to move on and be happy and he confided in me during their break up. So no, I'm not a homewrecker by any means, I didn't even think our relationship would get this far. I mean they had just broken up, he already had kids with her, and at that time I was just a listening ear. Now that we're married I feel like she needs to get over herself and chill out with the name calling and threats. Its been a year now and she's still playing tic for TAC. It hurts my feelings that she's bringing innocent kids into the situation and trying to make them not like me. I don't want them growing up hating me. Idk what to do to make them feel comfortable and loved than what I've already tried to do. I try playing with them at the park, buying them things, holding them when they cry, talking to them, yet they still run away from me and repeat the bad language they've heard from their mom...helppppp!!