UPDATE: in case anyone is interested...
The vet was out yesterday, not my normal vet but one from our normal clinic. Her opinion is that although my horse has many issues, none are so bad that requires the horse to be put down right now. In fact she thinks she looks very good for 28.
She OKed the use of Bute on a daily basis, which went against my normal vet recomendations to help manage pain (something I wanted to do months ago, but was advised against it). She also said the horse was most likely anemic coupled with the heart murmur causing her heart to skip a beat which lead to her passing out and falling over when she slept. She had a fancy name for it and I'll probably spell it wrong - senastion. But because I put her on Red cell, it built her blood up and "reversed" the anemia.
I guess the bottom line is: she is doing OK, not great, but not horrible - we'll re-evaluate at winter.
Thanks for all the warm wishes, thoughts and hugs - you all are GREAT!!!