Having been a Bills fan all my life, it would be very hard to support them if this were the case. Winning is not everything. I would find it very hard to support him or the team if he signed with the Bills. At some point, you draw a line.
I guess the closest we've been to this is OJ situation. I appreciate what he was for the Bills back in the day, but as an organization (and I think as a fan base) the Bills have distanced themselves from him, and that is the right move.
Anyhow, by now I'd be looking for any small way I could to voice my displeasure. I would also be looking for another team to root for, but that would be hard after so many years of emotional investment in one team.
As I said, at some point you draw a line.
For the life of me I cannot understand why the Browns would do this to their team or fans. Greed (and latent stupidity) is blind. At least the Dolphins were smart enough to have some out-clauses built into their offer. Now we know why DW didn't take their offer.