Am I wrong? [I Need Advice]

I’ve been in a relationship about 5-6 years now. This man has 6 adult children. Never have I gotten a card or gift on any occasion or even a text. My birthday came and went again nothing. But every family function I have attended for him. I even hosted the Mother’s Day party at the house for about 30 people I did everything while he got drunk did nothing. I did it because he’s a widow and the kids miss their mother still after 8 years. Recently I decided to stop doing family functions with him because they just ecnor me anyway and it’s no fun. Being that we’re not engaged and never will be I decided I enjoy not being around them even though when I see them I’m very nice. Well, next week he’s throwing another party for the eldest step daughter she’s 45! I told him I won’t be home and gently explained why. He blew up and said I should be there for him? He blew up with rage and said than he’s done with me? I don’t see how it’s fair? I explained in 6 years nothing is ever done for me not even a text happy bday but I always help him with their bdays and party’s at the house and he agreed but still thinks I’m wrong? He never throws me a party and invited them. There’s a party or function almost every month! Is it wrong fir me not to be here or want to be here?