I don't know know how 2 deal with the baby momma drama in my life anymore

I've been with my boyfreind for about 3 years. His daughter was 2 when I met him. His daughters mother and he were broken up since before she got pregnant. When she got pregnant he was there for her during the pregnancy and has been a wonderful father...

to his daughter. he has always been upfront with her about not wanting to be with her. Main reason is because she is a very mean, materialistic, aggressive person. Shes was always trying to get back with him. His daughter is going to b 5 on Sunday She loves me and I love her as well. her mother has often called me names but does say that I am good to her daughter. For the past three years baby momma has been nothing but rude and malicious to me. Phone calls, threats, etc. I've respond with silence bc I wasn't raised to be confrontational. Also, I don't want to disrespect his daughter and I don't want to cause him more problems.
So its been 3 years of this and I'm sick of it. I don't even want to be near her. Its gotten to the point where I'm considering leaving him because of her. His daughter is displaying characteristics of hers and I find myself resenting her and not wanting to b around her as often. I think about my future and the constant compromises I have to make just to b with him and I feel frustrated and confused about what to do. He's the best boyfreind I've ever had and I wonder if I love him enough to sacrifice my life for him. She stresses me out. I wonder if I'm becoming petty and vindictive myself. I don't want him to give her back to her mom in clothes that I buy her. Reason being bc the last outfit I never saw again and when I asked his daughter what happened to it she said her mom sold it at her garage sale. So, shes makeing money off of me...
Recently I wanted to do something special for her 5th B-day. We spoke about a bunch of different ideas. Somehow baby momma asked him why she wasn't invited and him being the nice idiot that he is said o, you could come. I kinda freaked. I don't want her at the party that I planned with him. She will embarass me and him infront of our families and friends. My family will take it out on him and will not like my relationship with him. So, I decided that my family and myself were not going to go. I don't want my family around the negaativity. He told me that he'll say something to her. But that will cause a massive fight between them, plus I told him she does have the right to b there, its her daughter. I'm just the girlfriend...

I sometimes feel like I want to leave. I'm sick of copromising with, him, his daughter and the ex. I love him immensely but I don't know if I'm wrong or right in the B-day party situation. I don't know if I should stay or go in this relationship. Maybe their is someone out there that has gone through this and could give me advice. What should I say what should I do? How do I walk away from the man I love just because I hate this woman. Do I compromise the rest of my life or do I call it quits and try again w-someone else. Who knows if I'll ever find someone like this? Please give me any advice...

D-