I'm pissed at how fast my mom is marrying again after years of abusive relationships.
What do you mean about your mom's past abusive relationships?
She's not going to die from her abuse, she's going to bed a son of a bitch.
It's normal and acceptable to have concerns about the well-being of a family member, especially one as close to you as your mom.  You can't stop your mom from making a decision but you can give her an outside perspective on her relationship that will be valuable and useful to hear.
Nah, I'm gonna tell her it's either them or me.
If you think that your mother is marrying someone too quickly, you should try to talk with her and raise your concerns about her relationship. She loves you both, so don't make her choose how to divide that affection.