On one hand, I agree with Elana. For a horse that's relatively new to you (only had him a couple of months, right?) you are doing him a profound favor by letting him live off you for as long as possible.
Many people, myself included, would likely have him put down just because he hadn't earned his keep (and some would likely say that makes me cruel as well). On the other hand, if it was a horse that I had owned and ridden for years and absolutely loved, then I would do my utmost to give him the best and longest life I could.