Should I do this or not?

So...he seems to not only be controlling, but just a jerk in general. Well, you are in a bit of a situation, because naturally, as a mother, you just KNOW what's better for your daughter. It's a weird, ridiculous power that mothers have. But if she's in denial then she clearly sees something in him, but idk what. Problem is, if you don't allow her to be with him, she is going to be with him. Get me? People want what they can't have. And your daughter wants him, for some reason. The only thing you can do is sit down and talk to her, and be brutal about it. Point out what you don't like about him to her and why it will affect her in the long run. Tell her you are on her team, and not her opponent. Eventually, with or without your help, she will realize everything, but the sooner the better. Because a teenage heartbreak these days is equal to a divorce from a marriage of 30 years. Just try and talk to her more, but don't "Ban" her from seeing him. Because it will only spark the flame of resentment and rebellion.