I feel so lost...I need help

My step mom and dad have always accused me of being inconsiderate and selfish because I’m still going back and forth between my mom and them. And as back story, my dad and step mom HATE my step dad and mom.

My brother moved out when he was 15 to go live with my dad and step mom and since I didn’t do that they use it and hang it over my head when we get into arguments. Today I told them my boyfriend, of 4 years may I add, was in Oakland for a job. I was asked who gave him the opportunity and I mentioned my step father did. They go off saying how “oh so they help your boyfriend out but not your brother?” And “you didn’t even step up for your brother?” My brother is 20...

Anyways this goes on and I’m getting confused because I was told by my step father that he did offer my brother the job and that he declined it. But to my understand now, my step father didn’t actually do anything. But just the things my step mom was saying to me was so unbelievably rude and uncalled for. She said that I was an “inconsiderate asshole” and mentioned how my boyfriend isn’t even family and she only says that because I never ever have my boyfriend over at their house because I hate it there. And second of all my brother never even contacts my mom and when my mom dose contact him he never responds....

It’s just every time something like this happens it’s always my fault because I “didn’t stand up for my brother” or I didn’t leave my moms and because I didn’t leave “I’m enabling this behavior.” So now my brother is mad at me. I don’t even know why!!! But after I went into my room and talked with my boyfriend about it, that’s how I came to find out that my step dad even told him that my brother declined it! I went back out and told them this how I didn’t even know, my boyfriend didn’t even know and that we were both lied to by my step dad. That seemed to calm my step mom down because she realized that I have no fucking clue and that my brother had no clue. I’m so so frustrated...