As someone said above you can try hammering a slightly smaller SAE socket on but it better be an inpact socket (black type) else you'll likely split the socket. A standard POS Sears socket will likely crack in the corner of the point valley.

Worse comes to worse you bust the nut and stud off, and then you'll simply need to pull the strut and replace the strut hat. It's not the end of the world but a waste of a perfectly good few hours some weekend.

I'd swing by the local dealer, buy a full set of new nuts, give the clerk a sob story and see if a free mechanic could give you a hand at popping the nut loose for a second or two.

Never hurts to try...