AITAH for feeling struggling with my boyfriend’s family

I have been with my boyfriend for a while, and overall he treats me well. However, I’ve been struggling with his relationship with his older sister and his mother,especially when it comes to money.

From the first time I met his sister , she has made comments about how it’s “natural” for a younger brother to financially support his older sister. She often says my boyfriend should work hard to take care of their mom and sister.

He got like 6 siblings, his parents divorced when he just a kids and he even didn’t stay before with his parents and been take care by relative. His sister and mother was thinking I keep using his money and take him away from them. I didn’t do that and what they don’t know is that, he not really close to his family and even rare to talk with then and I’m the one who try to fix their relationship and when he saw how my family treat us well he said that he will try to nice to his family. But they still think that I’m the asshole who took their brother/son from them. Last year we go on a family trip with his family, I always carry my boyfriend wallet together with me, and the next day his mom try to take his wallet but my boyfriend was angry about that and his mom and sister start shouting and screaming at us and they feel unfair like why I can but they can’t. I felt very uncomfortable. They even didn’t say sorry on that.Especially his sister and her mother. They even didn’t treat me with respect and friendly attitude.

His sister:

Sometimes when we go shopping together and I buy something with my own money, his sister assumes my boyfriend paid for it. She’ll then say she wants the same thing and ask him to buy it for her too. This makes me feel uncomfortable, especially because I earn my own income and pay for my own things. There was also a time when she borrowed money. I happened to have cash and lent it to her. Later, she acted as if the money came from my boyfriend. When he clarified that it was actually my money and that she should return it to me, she didn’t acknowledge it. In the end, my boyfriend paid me back himself. On her birthday, I suggested buying a cake. Later that night, when my boyfriend said he was hungry, she commented in front of me that the cake didn’t taste good and he could just finish it. I felt embarrassed.

His mother:

She always think that I’m took her son away from her and always use his money. But hey , I earned money too and some of his stuff is brought by me. And she always talk about money with my boyfriend and always ask money to help his siblings. Why she don’t ask from others? Because she knew that my boyfriend was so heart soft and the other siblings always ask money from her and he is the only child who didn’t take money from her. When she saw the stuff I used was quite expensive and saw me shopping, she think that I keep using her son’s money and that’s why he busy with work. But the truth is I’m using my own money for that and my salary even higher then his one.

His other siblings

His second elder brother was nice to me and for me he is the most “ normal “ person in his family as he know I’m the guest. The others like his elder brother and his wife is fine for me as we don’t always meet but still seem fine , and his elder sister like what I had said. He got another two younger brother and sister ( from different father) they like don’t talk to me and even sometime I try to nice to them and paying for meal and present ,not even “ thank you” will be said by them.

My boyfriend is generally kind to me, but this situation with his family has been bothering me. My family angry with what they did to me and I always struggle that if I marry him and I need to face his family for my whole life. I love him but I can’t accept his family even sometime I avoid to meet his family and as I dislike his family. When they ask him out, I will be like “ I don’t want to go out with them “ and my boyfriend will decline their invitation and stay with me. Sometimes we even fight because of them.I hope that he can be with me forever without his family together. Am I too selfish?