"You know, W, it's been really great spending time with you recently. But [your boundary discussion goes here]."
Yep -- good. And for gosh sakes, DON'T say something like "it just hurts too much." It's not attractive. Instead say "it's disrespectful to me, to our marriage and to our family," or simply "this isn't working for me anymore."
No melty man, no passive-aggressive anger, and no puppy-dog supplication, either. LEAD.
Your marriage -- and your family -- needs a hero right now, and it certainly AIN'T gonna be your wife. That means you, buster.