If you check your feelings of entitlement to the shared space she has continued to pay for, and your saltiness over the friendship, you can have a perfectly amicable roommate relationship going forward.

Tell her that since she's been gone a while it might be a good idea to chat about how to keep the shared space comfortable for two people again. Don't be a dick and tell her how much more you love it when she's gone and just paying half your rent. Instead, agree on things like:

Quiet hours

When cleaning needs to be done

how long can dishes be left out

Designate a place for her to put your things if you leave them out

Respect privacy when in your rooms

Keep it civil and now you know you'll want to live alone when you can.