My old cat started peeing on things since we got a new cat Will she continue if I get rid of new

I have had my cat (camo)for about four years and she has never peed anywhere else but in her litter box. Recently I got a new cat (hoping they would be friends) and my old cat has started to pee on my hard wood floor and in other random places. I am not sure if the new one is peeing too bc i have only caught Camo in the act. I have given them two litter boxes downstairs and one upstairs. Recently  I have separated the two cats (one upstairs and one down stairs) hoping that would help but my cat still peed on the hardwood floor. She still hates the new cat. I am wondering if I get rid of the new cat will my cat still need to mark her territory? She never peed like this before but will this be a new learned behavior even if she goes back to being an only cat? I need serious help with this. We just got new carpet and new floor and with all the cat pee it has ruined my new vinyl flooring and it is now peeling up. And permanently smells like pee.  I have now had the new cat for six months and their relationship does not seem to be getting any better. I love both my cats but especially my old one I don't know what to do. Currently I am trying to get rid of the new cat but I will deeply regret it if my old one still chooses to pee on things. HELP!!!
Ps she does not have a urinary infection I already tried that.