TTC???

My husband wants another baby. At first, I thought I did. I'm 37 and he's 39. We have four kids, 17,12,5, and 3. Am I wrong for lying about my ovulation schedule? I've tried subtle hints about not having another baby but he thwarts every attempt. He's super excited about having a baby and I'm super over it. How do I tell him I don't wanna gain 40 pounds, have back aches, and swollen feet again?