Oh yes, I had the constant guilt. I stuck it out until I had to put my last horse down, but every day, every time I saw them, and every time I thought of them, guilt, guilt, guilt. I was not able to keep them up to a decent standard (at least for me), and I got so tired caring for them that I had no energy to ride.
I had the bad pain in my back from a bad car wreck decades ago. It took years to heal enough so that riding did not hurt my back. Before I had innocently thought that NOTHING would ever stop me from riding, but for several years my back pain did.
I found one homeopathic remedy that helped my chronic neck pain (from the wreck). It is--"Sciatica--Back Care" from Newton Homeopathics in Georgia (http://www.newtonlabs.net). Their phone is 1-800-448-7256. I also use it for my leg pains if they get bad, expecially from my sciatic nerve. It is for "Helps relieve symptoms such as inflammation, pain, tingling, and numbness radiating from the lower back down the legs." I accidentally found out that it helped my neck much more that the homeopathic neck remedies. The thing with homeopathic combination remedies is that you just have to take one drop, you have to bang the bottle against your hand around 10 times each time you take a drop, and you stop taking the remedy if you get better, only using it again if the pain comes back. You do not take it every day like allopathic medicines, only when the pain bothers you.
If this helps enough to start riding again I would recommend that you WALK for months. I'm 60, I started back riding again around 6-7 years ago. I took it SLOW, I still take it SLOW, I listen to my body and take things SLOW. Since it sounds like your horses may not be very fit this will be good for them too.
You are a lady with a lot of guts! I look forward to getting to know you.