Getting along with my husband's baby mama. 🙃🔫

Ok, so I'd like to get along with her for my stepdaughter's sake, but she doesn't want me at drop-offs, she hates me, has made it abundantly clear she wants to beat the crap out of me, and says she doesn't want me doing anything/buying anything for her daughter, and if I do, she's gonna light it on fire because I need to "dress my own kid." (No bio kids yet.) My stepdaughter is two, and she loves me. She's always attached to my hip when we get her. Her daddy acts like he's gonna "get her," and she runs to me to protect her. 🙈❤️ I love her. Her mom is always badmouthing me (she doesn't know me, has never even spoken to me. Just jealousy), and honestly, her daughter comes to our house and says "bi***," because she hears mommy saying it! I want to get along with her but it's seemingly impossible. Anyone have any advice? Please help. I think my stepdaughter needs to see us get along. We need to be able to be at public events for the baby together (in the future). I don't want her jealous mom turning her against us in the future or making me seem like the wicked stepmother. She has it in her head my husband cheated on her with me and left her for me, but he left because of the constant fighting and her accusing him of cheating, then met me two and a half weeks later, while working on my house. (He does repairs.) She makes it seem like I broke their family up and just absolutely hates me.