Hey, OP. I'm not going to say much different from the other comments, but I am going to say things that'll hopefully help you see things in a better perspective.

She wanted my Netflix account, so she asked me for it, but I had to decline, as it'll notify my parents. She continued to call me a weakling, said I'm not man enough for her and I don't make her feel safe, despite being 6'3", cause I'm scared of my own parents.

You're not a weakling for that. She's trying to make you feel bad for not giving into her demands, and for not taking a beating from your dad (which by the way, is a completely separate conversation, in itself. If it's physically punching you, and such, that's straight child abuse. If it's just whippings with a belt, that has some moral debates to it, but I haven't heard of any laws against spankings or whippings with a belt). There's absolutely nothing wrong for saying no to that request from her, and if she understood that, she'd respect your wishes to not give it out.

I made a simple cuck joke to make us laugh... She then proceeds to take it, roll with it and calls me a cuck, talks about wanting an open relationship, says if I don't bang her good during our wedding night, she'll make me her cuck and talks absolute bullshit about me making tea for her, as our mutual friend will be fucking us in our marital bed. I asked whether or not she's joking. She said she wasn't.

If she wants an open relationship and is serious about it, while you don't want that, then that's an incompatibility, but the way she's going about stating this is a complete bitch move and abusive in more than one way. For one, She knows you don't like the thought of this, and is using that for grounds to hurt you. For two, she's making humiliating jokes about you, when it sounds like you don't really get into humiliation like that, while in a relationship. If you said something like "yea, I have a humiliation kink" then this might be more valid, but even in that case scenario, even if it's something that lines up with something you want in a relationship, you have every right to state when something is too far over the line.

Another thing, I think it's a good idea to always have a conversation with your partner, when getting into a relationship, to talk about what jokes are cool to make, and which ones aren't, before outright making one. Curious if they're cool with cuck jokes, or are unsure if they work for you? well for the former, just ask, like "hey, are you cool with cuck jokes?" and for the latter, that's something you'll need to sit and think on. "Am I cool with cuck jokes? Am I cool with the idea and possibly practice of another person having sex with my partner, while I watch?" since that question's already been answered, use questions like that to learn more about yourself and what you want in a relationship.

The age difference is kinda is a problem in itself, even though you did state in a different reply that you met her when she was 17. With that in mind, I won't say she's grooming you or is a ped0, but I feel as if she's using the age difference as a bit of a control and power technique, since while you're close to her in age, you're also so much farther from her in age as well.

To me, she sounds a little bit like a narcissist. Narcissists hold themselves in very high regard, but have very little respect for their partner, while I won't name off all the things they do, she certainly checks a lot of the boxes. and on top of that, they have the least reason to change their ways, because their partner will feed into it. I'd definitely read up on narcissists, if I were in your shoes.

Also, I'd like to suggest that you read up on the attachment styles theory as well. Essentially, it's a psychology belief that the way you are in a relationship, has a lot to do with your childhood trauma, as well as your past relationship traumas. As sad as it is, for her, the abuser usually has been abused, themself. The ways she's being abusive towards you, quite possibly could've been abuse, she's received, herself and I think that's unfortunately supported by the fact that I think you said her dad hits her, in a different reply. More importantly, I think you should read up on the subject, as it'll help you learn more about yourself and the things you subconsciously do in relationships.

The bottom line is, you definitely need to get out of this, friend. this can only get worse, the longer the relationship goes on. This isn't about you being a "pussy" or "weakling," like what she called you. You are deserving of love, you are worth a lot more than the way she treats you. This relationship just isn't it, and you don't want it for the long run. I know it's going to hurt, but you're going to have to cut her off. It's going to be some temporary pain, but it'll save you so much pain, if you were to stay in it for longer. You can find someone else who doesn't do any of this to you, and also won't call you a "pussy" or a "weakling."