It's good that you're aware of how alcohol can alter people's behaviour. You can't spend your life getting drunk every time you want to be intimate.
It sounds like you've never really been on your own. I personally feel that a person needs to know how to be single before they can be an equal partner in a relationship. Salt has a hold on you because you "need" him.
It sounds like a very dysfunctional relationship, and I'm not sure I would classify it as polyamory. It sounds like he cheated on you, and then "informed" you that this was now an open relationship, because he wasn't willing to give up his new toy, but nor was he willing to give up the comfort of having you around. Where was your say in all of this? How were your needs being met by this arrangement?
Even though you don't consider that your "poly dilemma," it's very central to your current situation. It's going to taint everything you look at. You see these two friends with their great relationship and think "I want that too" so you figure, why not join theirs? The problem is, you haven't dealt with yourself yet.
My advice is that first you need to leave Salt and learn to be single for a while. Don't just jump from one relationship to another. There's no rush. You're not even 30, you're just a pup. At 25, your brain is just now finishing to grow.
For 20-25, two relationships is about 3 too few, not 1 too many! How do you figure you even know what you like and dislike in a partner, with such a small sample size?
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker