I really am pathetic

My best friend and I got into a fight last night, that started about how she didn't like my boyfriend. It shifted into how I've been acting bitchy towards her and her family, that I'm a toxic person and then the end was an ultimatum, break up with my boyfriend or we can't be friends anymore.

She did this a few years ago, but it was fully justified, he was a huge N and I didn't see it no matter what she said.

My actual family is a fucking mess, my dad was a marine with a sensitive temper and seemingly infinite narcissism, my stepmom was both an enabler and narcissist, she had a magic talent and habit for talking you into feeling like you're worth jack shit. My biological mom was a stripper, never graduated highschool and wasn't able to keep/take care of me after I turned 6ish, just recently tried to get back in touch.

My best friend and her family took me in about a week after my 18th birthday, it felt good at first, but now my best friend and I can't seem to stop "fighting". She blames my boyfriend for the way I'm acting, but says I've been bitchy to her since I broke up with my last one, is inconsistent but she's so passionate and it's like she's desperately trying to get me to understand something.. I honestly don't know what to think or feel anymore. I've trusted her more than anyone for the past five years and she says I don't care about her, that I do whatever I want without considering her feelings, I'm toxic and have been treating her family and her like shit. I'm so confused, is there something I'm not seeing that she can? I felt like I was finally making progress... I've been crying for a bit now, I don't even know what about exactly but I just hurt. One thing that keeps going though my mind is how well she gets along with her mom, that she'll always have that no matter what, and I honestly don't believe anyone will care about me like that anymore. I'm not worth it.

I'm so fucking pathetic I was literally about to go cry to her 12 year old sister who is used to being yelled at by her... Here I am, an 18 year old who is trying so hard to become independent and healthy, broken to the point of trying to find comfort from a middle school kid who needs me to be strong for her. Why the fuck am I like this? Why can't I just... I don't even know anymore.