I have a different perspective, I think. Not only think about what is best for Cinny, but waht is best for your young family. You have a young daugher, right? Do you have any plans to have another child? Think LONG term. I am so very glad that after a 6 year gap, my husband and I went for another child. I wnted a third, but he did not. But having two children has made a huge difference in our lives as middle ages parents, and the benefit will be even more noticeable as we age. I wish I had three, or four, but that's another story.
My point being, if keeping Cinny is a financial strain at this point in your life, maybe you should consider letting horse ownership go for a few years. Focus on your family, if you do think another child is in the cards, go for it. Build some financial stability, and heck, start saving for your retirement.
I know this all sound horribly stodgey and colorless, but you aren't a teen , and when all is said and done, family comes first.
AND, now for Cinny . . . If the girl is on the up and up , life in a pasture with a few other horses will be absolute heaven for Cinny. And you would have made that possible. Quite the gift of a lifetime.
IN time you can get another horse. Maybe one that your daughter will share with you?
So, my advice is to lease Cinny for a trial period to verify that his treatment is good before either long term leasing or selling him. Hold off on horse shopping. Take lessons on a school horse and put the extra time into the family. I know that sounds like a party killer, but them's my thoughts.