[Roswell]

I think it has to depend on your read when he flat called the flop. Does it seem like he's on a flush draw?

I would probably bet $1000 on a non-diamond turn. If he raises his additional $1500 and you feel strongly he has a set, I don't think you are committed, and you might be able to lay it down. This is player-dependent and read-dependent, so advice on the internet is not a huge help.

On a diamond turn, maybe bet $800, which gives you more wiggle room.

BTW, I have just started playing in this game every weekend. It is amazing.