Okay, you need to step back and take a deep breath... Maybe two or three of them. Now, you say Ricci is your heart horse and your best friend. What about your other horse? She is fairly young, isn't she? Maybe at this time in your life you can do with just one horse. Sell the other horse and concentrate on Ricci right now. With one horse your expenses will be less for all things, board, feed, vet, farrier.... Sometimes one animal of any kind is just overload at a time when you are feeling your worst. Sometimes having just one "heart" animal is what will make you think and see clearly. When times are better and pick up, then maybe you will decide to get a second horse, that doesn't mean you have to have one now. Besides, you can only ride one horse at a time.
As far as the vet. I work for one and we have people that have to deal with the issues you have, no money to afford an emergency... But, we have also worked out things with them, sorta a barter. They come and work, cleaning stalls, cleaning cages, walking dogs, mainly the "dirty" work, but it seems to work for special circumstances. I am not going to say"see if you can make payments" because most vets are in the financial dumps like everyone else these days. But, maybe you can work off the labor part and just pay the actual cost of medications. Talk to your vet, it might work.
If for some reason when you did the polo wraps too tight or wrapped the wrong way and it bowed her tendons, so be it. Don't beat yourself up about it, its done and over with. You can't go back and do it over and if indeed that is what happened, then you need to move on. Help her by hosing those legs and doing what needs to be done now. If she is not lame, that's a good sign.Maybe hosing and some rest will help. Again, EVERYONE makes mistakes and sometimes it effects our beloved animals, but if there is anyone on this list or anywhere who owns animals and says they have never done anything wrong, they are not telling the truth. From wrapping a leg wrong, to tying up a horse wrong, everyday we all do things we later wish we hadn't. I have a show dog that had a few mats on his back leg. It had snowed and he had some snow/ice wrapped up in the long long feathers. I had to hurry in to work and figured I would clean it up when I got home. Well, he chewed his hair off, right down to the skin and made it bleed. I was SICK about it and kicked myself because if I had taken a few minutes to brush the mats out it would have been fine. I had to treat his HUGE red oozing area for weeks. I was so mad at myself. But, at that point, nothing I could do would take back those few minutes. Had to move on, he is fine now and just got his first Championship points at a show a few weeks ago. I know this is not a horse, but I have shown/groomed dogs for years and knew better, but made a mistake. Was I mad at myself? Yes, I sure was. I was so upset. We all make mistakes. You did not do it intentionally, it was a mistake.
So, take a few breaths and quit crying and relax. Go hug your girl and think about what I said and what I am sure others will say. Step back and reevaluate how things are. If you need to sell your other horse, then do so and it will make things a bit easier for you. If you want to keep both horses, then start thinking of ways to "barter" for things you need to have to make your life easier for a bit until things are a bit clearer.
Have a good day, sending nice thoughts your way