I really should not have gotten a cat with my girlfriend
Why wouldn't you get a cat with your girlfriend?
The cat doesn't help me at all, it's a creature purely focused on pleasure.
You should do your best to take care of any animals that you've adopted. If you no longer want the pet then you should think about giving it up for adoption.
I'm going to get rid of pain of having a cat and set him free.
It is okay to no longer want the cat but since you got it, you should be responsible about rehoming him. You should make sure that he is going to a safe home.