You should seek professional help if you are 1) doing it to her every day even when she says stop repeatedly 2) you do it until the point where she pees (or loses control of her body, it's appeared as both in similar letters) 3) you're pinning her down against her will daily for this little bit of torture that you enjoy, and that she doesn't.

Maybe your wife likes it. This LW clearly does not. Tickling has been used as a form of torture so it clearly isn't always 'just tickling'. That's probably why it's also used in BDSM.