I'm making vodka sauce and used whole milk instead of heavy cream... it looks like it curdled

I'd strain out the curdles, but in future use the cream. You need the fat in there to prevent the curdles. If your sauce lacks richness after you strain it, I'd add cream or maybe a little butter or even sour cream depending on your sauce recipe.

It would help to know more about your sauce... what are the ingredients?

Meanwhile, here's an article on fixing broken sauces
https://food52.com/blog/14876-kitchen-rescue-how-to-fix-a-broken-or-curdled-sauce