Friend’s abusive fiancé *trigger warning-abuse and rape*

I need advice, because I’m really not sure what to do at this point. I have a friend and her fiancé is verbally and emotionally abusive. I’ve heard him threaten to hit her, but as far as I know it’s never actually happened. He’s said some awful things to me as well, including telling me that if he ever stayed in a hostel, he would rape every single girl there due to easy access. He would call my friend stupid, a pig, dumb bitch, etc while she was pregnant. If she made a mistake, he’d say “I’d be smacking the shit outta you if you weren’t pregnant right now”. I don’t like him for obvious reasons. Well, here comes the difficult part: my friend just had her baby a month ago. He’s precious. I was the first one to meet him, not her fiancé. He couldn’t be bothered because he was sick, but doctor had said he could come as long as he wore a face mask. Anyway, while she was pregnant, I told her we should go out for drinks after she had the baby. I meant the two of us. Now she’s been asking me a lot lately when I’m going out for drinks with her and her fiancé. I’m not comfortable being around him while he’s drinking. At all. But I’m worried if I tell her that, he will read the message and hurt her. I’m really not sure what to do at this point. I keep coming up with excuses to not go out with them, but I really do want to go out for drinks with just her. Mostly so I can get her away from him and try to help in any way I can. I want to keep myself safe, but I also don’t want my friend to get hurt in the process. I’ve told her several times now in person that I’m worried, but she always just comes up with excuses for him