I don't want to entertain negotiations if I can.
Do not do this. I think mendhak was stressing that point with the bold font, but after you say you're going to leave; do it. No matter what. If they offer you an increase or whatever perk, don't take it. You're on the chopping block as first to go if/when downsizing comes around. All the necessary precautions of you leaving will be in place within a week of you rejoining the team.

Not to mention, the work relationships take a hhhhuuuugggeeee hit. Your boss won't be so trusting anymore.