I mean... sure, of course. We all know that.
What makes this communication not good? Or how does it constitute "telling everyone everything?" Do try to keep your self-confessed bias in mind ...
Bear in mind that Sven has literally just learned that something else he was trying to keep "on the down-low" has just been "blabbed."
It's barely a hop, skip, and a jump to come to the obvious conclusion that in this particular social group, the odds of him also keeping secret the fact that he donated quite a lot of money to her campaign are also quite low. It's also not difficult to further conclude that if she's gonna hear it, it would be better for her to hear it from him.
And as to the amount... well, she asked.
I am imaging right now what would have happened if he'd kept quiet about it, then a couple of weeks later she'd heard it from someone else, and become quite angry. I would bet a dollar to a dime that the same people angry at him for confessing right now would be just as angry in this alternative scenario.
I daresay that we have a classic "last panel" effect here - there is May, looking grumpy in the last panel for hours on end, and so no matter how ephemeral that expression might turn out to have been when we open tomorrow's comic, that impression it leaves on us is a strong one.
May will be fine. And if it turns out that they no longer feel able to have sex, well, it was fun while it lasted.