I feel I sacrificed one cats health for my other cat

I adopted a catchoo cat, my girl maple she was diagnosed with the cat flu treated and vaccinated, trinity my other cat is up to date with her vaccinations but I can't be sure of the cat flu vaccine was one of them, I felt I weighed the pros and cons and the risk of trinity getting cat flu but decided her having company was worth the risk I now feel guilty as she is showing signs of the cat flu such as sneezing, snoring and breathing noises she still eats and drinks normally she also shows symptoms of rare vomiting and diarrhoea which may or may not be related as she struggles with fur balls and is sensitive to some foods I have 4 weeks before I can afford to get her to the vet and just need reassurance did I weigh up the pros and cons correctly? Has anyone else had a cat showing the same symptoms but not affected by the cat flu? All advice welcome

Unfortunately, it is impossible for us to offer an analysis of the pros and cons without knowing for sure what is wrong with her. Only a vet can tell you that for sure. At this point, also, what's done is done. If you thought about it and weighed the pros and cons before, then you made the decision you thought was best at the time, there is no use torturing yourself over it now.

Lots of vibes to you and to your girl that she will make a good recovery.

This behavior is actually common when bringing in a new kitty.  Your resident kitty's territory has been invaded and she's stressed out.  Keep an eye on her and make sure she continues eating and using the box normally.  Give her A LOT of extra love and attention and "protect" her from the "invader" if need be.  Always, always, always err on the side of standing up for the resident kitty (your first kitty not the new one). 

They have loves together for a year now so I don't think the invasion still has an effect and yer can't help being protective over resident cat trinity as she is the timid submissive one but I will take her to the vet and try not to torture myself over it just so hard to think I may of have trinity the cat flu by getting maple

For an update, the cat flu vaccination is part of her yearly vaccine so she was always vaccinated, and he said she was healthy

I'm so glad to hear that she's okay!