I feel like my brother stole my best friend/ groomed her

So my brother (M19) is dating my best friend (F15) for like over a year at this point.

Their relationship is far from perfect or even healthy. Mostly it’s because of my brother’s controlling issues and he picks majority of their fights. But they always find a way back to each other. For the longest time my best friend told me they weren’t having sex and it was completely platonic between them and I honestly believed her until she drops the bomb that she was pregnant. Which means she had some explaining to do. That’s when she originally told me this whole tale that they did it only one time and she was the one that pressured him and she wanted it.

Now fast forward to the other night I slept over her house to help with her nursery and my brother is away at basic training. So it was fun that it was only us two and not have my brother linger closely by. However that’s when she started opening up to me about a lot stuff about their relationship and one of those being like their sex life and that she actually lied about it because my brother told her too. They did it way more than the one time like she originally said and she states in like a funny tone that she basically lost count and even did home movies and like he taught her to do certain sexual stuff…all summer they were smashing and even snuck off a couple times just to do it. We went to six flags last summer and remember they went missing for like 2hrs and she confessed that they did it there too !! But she told me they almost got in trouble their, apparently a mom was concerned and saw them snuck into the family bathroom and my brother looks alot older for his age due to his beard. especially compared to my friend who’s a bit of late bloomer with a baby face because of dimples plus she’s also a tiny thing I think 5ft and my brother 6;3…so outside POV it looks highkey wrong.

But this is where I think my brother is a groomer or just like messed up. Because she told me about the night she lost her virginity to him and she retells me how it happened. It was the first night my parents allowed them to sleep in the same bed at night. (my parents approved their relationship. )But what she told me that is she was really nervous because he locked his bedroom door before he got in the bed with her. She said at first they barely touched and he asked if they could cuddle and they did, after awhile she said they end up kissing and his hands were like wandering over her body and she told me he got on top of her while still kissing her and he started to like remove her clothes and before he inserted himself in he covered her mouth with his hand and basically had sex with her. She told me that it hurt a lot and that she couldn’t even tell him to be more gentle with her because he had his hand over her mouth and basically his entire body weight on top of her and she felt like she couldn’t breathe. She told me after they were done she kinda just layed there in shock until he fell asleep and when she went to bathroom and saw blood she was really confused and she had to google to know if she had sex or not.

( yes my friend is innocent one she didn’t know much about sex her parents are super religious nuts and strict. She thought sex was being naked and dry humping each other….If she asked me about it I would obviously gave her the tea about it but she didn’t, I try to keep it clean with her because I don’t want to come across as a friend that’s a bad influence or someone that peer pressures her)

After she learned via google that she had sex. She crawled back in the bed crying to herself and she told me that she wasn’t crying because they did it, she was crying because she thought her mom would disown her if they found out and also she really didn’t like the sex so she sinned for no reason she felt. But She said my brother woke up comforted her and apologized for not slowing down To check in with her or asked her and they did it again that same night but this time she was more aware… But she told me she felt better about the choice because he was so sweet to her the next day and made her this care basket and gave her flowers. I remember that too but it all make sense why he was overly nice..but I also argue if she actually had a choice..

I know it sounds intense now that I’m reading it back but I promise you the way she retold this to me it was like It was nothing to her and she thought it was funny like a losing your virginity gone wrong story. When to me it sounds like my brother is not good person…she loves him alot and I don’t want to blow this out of proportion because she’s 6 months pregnant. But I also really don’t understand why she even loves him because he mistreats her a lot this would be novel if I go into EVERYTHING, I used to think she loved him because he knew her dad and she said when her dad was alive he liked my brother, but they weren’t even dating when was alive. But now I believe based on our conversations she likes that he fathers her..I honestly think she interprets him being controlling as he’s protecting her?

As for my brother he has had multiple failed relationships and I know why he likes her more for his Ego, prior to her entering a relationship with him…my bestie is obviously very beautiful and was very sought out by boys at our school. She’s very nice and is always put together. But she never really any interested to date any of the boys from our school. Because 1. She wasn’t allowed to date 2. She wanted a guy that goes to her church that her mom would approve of. Wouldn’t you know my brother picked up a religion ark and started to go to church randomly. But that’s all here or there I guess…

Unfortunately I don’t think she will ever break up with him unless he does something that affects the baby. That’s the only time I seen her actually get mad about something he did and stayed mad until he gave proper apology. But what she got mad about was he referred to the baby as a “little bastard” .

I’m just sad about the situation I feel like my brother broke my best friend. Even when I talk to her it’s like I’m talking to him now. I’m just mad and now grossed out with the situation.