Hi
Chances are if the rooster left that long ago the eggs won't be fertile (although it is heard of).
You have 3 choices, either:
1) Break her broodyness (you will find lots of info, just search "how to break a broody hen")
2) Once your sure she's sitting tight which is usually after 2 nights of sitting, give her some fertile eggs.
3) Let her be & don't disturb her (not recommended because she will lose a lot of weight with no chicks to show & some hens will die trying to hatch their broods.)
Its a real shame your not by me, I really need a broody!
Got a bodge job incubator at work instead
I gave up the wait after 2 months. I got a specific hen to go broody (cochin bantam) so I can hatch chicks & the thing lays an egg a day with the layers with no intent on going broody, just marches off the nest & goes into the pen with the layers twice her size for her day of fun, food & toys. Just typical!