"She says when she comes back we should make all these plans etc..
she even wants to go out for our anniversary."

She's simply saying anything to push you off so that you dont try to prevent her from going. She'll deal with whatever fallout when she gets back.

"My wife and I get along better than ever, except she claims she is not ready to give up OM."

the getting along part is her faking it.
the not ready to give up OM is the truth.

When my x was having her affair, she'd always get happy when she was on her way to see him, or on her way back afterwards.

listen to Starsky, his advice is good.

"In a ham and eggs breakfast, the hen is involved, but the pig is committed".