Having a hard time dealing with overextension

New to the mod playing as Goratrix and I managed to conquer half of France before I took over the entire house of Tremere. I now suddenly have so much counties and serious overextension problems.

I already made peace with the fact that I probably won't be able to do a world conquest which was my original goal, but the problem now is that Goratrix is ambitious and I can't let my vassals be independent without gaining about 110 stress for every one I let go. Could I get some tips for dealing with overextension? Is it still viable to try and paint the map my color?