Get the resume out. There will be overlap. Your tenure with the company may actually work against you since you're more expensive in their eyes.

When this happened to the company I worked for 10 years ago, I was one of the first people to jump ship. Of my 4 close co-workers that stayed behind to stick it out? Their positions were eventually determined to be redundant and eliminated within 3 years of the merger. Chin up; you'll make it through this.