My best friend/cousin is in an abusive relationship. What can I do?

My cousin who is also one of my best friends started dating a boy from youth group about 6 months ago. I started noticing red flags whenever he tried to have intercourse with her infront of me. Since I did not like him he told my cousin she was no longer allowed to speak to me. He took her phone and blocked me on all social media a couple of days before her and I were supposed to go on a trip to Boston (flights and hotel already paid for.) I drove to her house to speak to her but it was like talking to a brick wall. She confessed how much he yells at her and controls her but she didn’t plan on leaving him. I decided to separate myself for a couple months until my aunt texted me two weeks ago inviting me to have dinner with them. My aunt and cousin cried when they saw me and told me how much they missed and it was a happy moment. Then my cousin started getting calls from her boyfriend screaming at her for not responding to his texts fast enough. She was apologizing and ended up crying. She told me that he made her go off birth control and he doesn’t use protection. I have reached out to both my aunt and uncle but they seem to not care about the situation their daughter is in. I saw bruises on her stomach and she told me it was from play fighting. I tell her to end it but she tells me she doesn’t want to. I am trying to keep a distance but she keeps asking to hang out so she can vent to someone. My name on her phone is changed so her boyfriend doesn’t see that we’re talking again. She asks me for advice but doesn’t take it. I don’t understand? Why is she doing this to herself? What am I supposed to do?
My best friend/cousin is in an abusive relationship. What can I do?
Add Opinion