Did I do the right thing by giving up my cat?

I took my cat in 3 years ago as a stray kitten and took care of her ever since.. I got her spayed, got all her shots and regular check ups and she was always fine.. I lost my job and couldn't afford to keep up with her vet visits but I kept up all her flea treatments even though she was an indoor only cat and never had a flea problem. She started to scratch herself so hard she'd bleed and have sores. I tried different shampoos, kept using the Advantage flea meds that worked fine for 3 years, clipped her nails regularly but nothing helped. I put a cone on her to stop her from damaging herself any further until I could figure out what was wrong and even made sure to wipe her down daily and rub her so she wouldn't feel so irritated but nothing helped. I called the vet to see if they could see her and they wanted 100 dollars just to bring her in and that didn't include treatment for her and unfortunately I could not afford to take her. So I researched no kill shelters in the area and explained the problem and took her in a few days ago so she can get the help she needs cause she really is a sweet cat but I feel so bad about giving her up that I can't stop crying even though I know that keeping her would've made things worse for her health I feel like I gave up a child. I just couldn't stand watching her suffer and not being able to afford to get her the help she needed. I kept hoping something would come up as far as work for myself so that I could catch up on bills and take care of her again but things haven't been the best financially so I did what I thought was best for us both.. I just miss her so much it hurts.. I don't know what to do..