My heart hurts I don’t know what to do. What should I do?

Okay, long post and I’m sorry. this one is going to be a tough one for me to type out without shedding a tear. So bare with me. Starting off my boyfriend and I have been together a year and a half, Alright, so my boyfriends EX-wife hates my guts. I’ve been civil to her I’ve never said a harmful or disrespectful word to her. As soon as my boyfriend and I started dating she found me on Facebook and immediately told me that they had a daughter together which I am fine with. I love his daughter to death. And my boyfriend and I like to spoil her. His daughter is 3, the age where she is starting to tell little stories (lies). So there is no telling what she saying to her momma. It seems like everything I do. The mother has a problem with, I bought his daughter a necklace for Christmas and I forgot to take it off of her before she went back to her moms, and we asked for it back and the mother has yet to send it back, I’m pretty sure she probably, threw it in the garbage. The mother took one of my pictures off Facebook and starting asking people if they knew me, and finally found a girl who she knew worked where I worked and the girl said yeah she knew me, blah blah blah and the girl kindly let me know why was going on and told me to watch my back. A few weeks later my boyfriend said someone at work came up and asked my boyfriend the same thing, but this time it was his EX-WIFES picture and name. So she has little spy’s in my work place keeping an eye on her EX-HUSBAND(my boyfriend). So I let that slide until she pulled up behind my car one night, and that was he last straw for me. So I blocked her on every social media account I have so I wouldn’t have to deal with her getting my info.. so the past few months have been fine, then I decided to take his daughter out to ride a pony. Momma wasn’t having it and told my boyfriend that we were not to do that again and horses were her thing with her daughter( but she had to sell her horse a few months earlier?) so without consulting me about it. My boyfriend told her that we wouldn’t take his daughter out there anymore.. so not only did he shoot me down he is protecting the mothers feelings( the mother has been trying to get them to get back together with him for a year and he doesn’t want to go back) well out of the blue his little girl asked me if we could go and ride the pony and I was crushed as I had to tell her well go ask your daddy, when I knew the answer was going to be no. So we didn’t take her and hung out at his place and played. Well a few days later she messaged him because his daughter had told a story about how I bought her a horse back riding helmet and a saddle. The helmet was for her bike. Not a horse. The mother was livid, she told my boyfriend that if we were going to do that, we needed to have our own kids, and that his daughter is not and will not ever be mine... so I’m not allowed to bond with his daughter at all according to her. And my boyfriend is planning on marrying Me he’s says. I’m so lost. What would you do? Feel free to comment. Sorry for the long post.