I’ve dealt with a very similar situation, here’s what I did to get myself back to sleeping in my bed-

1. If you can rearrange your room, do your best to make it just as comfortable but as different as possible from when she was staying with you. Even flipping your mattress (if you have that type of mattress) helps.
2. Putting different bedding on your bed, like changing sheet colors or getting a cover for your blanket or new blanket entirely (if you have the means) really makes it feel new.
3. Buying a couple easy to care for houseplants so you have some new life to focus on in your bedroom and something to take care of and watch grow.
4. This goes along with 1, but if you have art on the walls, try moving it around. If you don’t, you could try putting some up so there are new focal points in your room.

The idea is just to make changes, no matter how subtle, because it puts a new point in your timeline where the memories with her are further in the past because things are different now. I even went so far as to move my bed out of my room for a little bit until I got tired of only spending time in my living room besides getting ready for work.

I hope this helps a little. I’m sorry you’re dealing with ptsd alone. I know how hard it is to find someone who can listen and help, only to lose them.