GOD you’re actual garbage let’s lay out all the reasons you’re an asshole shall we?
As stated above you’re not only minimizing your daughters feelings you’re projecting your own on to you daughter.
You can’t seem to accept the fact that your sister emotionally abused your daughter??? Or you just don’t care, which would make you an even bigger asshole.
You are trying to force her into a situation she has made abundantly clear she doesn’t want to be in. Doing so by threatening and punishing her like that’s going to magically change her mind? All you’re doing is pushing her farther away from you as her mother and her aunt that apparently loves her but has belittled her in the past.
(as stated in OP comments) Uh yeah if she wants to avoid Helen for the rest of her life SHE CAN. Stop trying to force a relationship your daughter clearly isn’t ready for or wants because it’ll make you feel better, that’s selfish. You also state you don’t invite your sister over but you don’t stop it either, so you’re willing to force your child to be in an uncomfortable situations MULTIPLE TIMES a week. Your daughter even tried to compromise with you and you couldn’t even do that.
YTA big time.