I'd still do a bit of overkill as to multiple text and log calls to request she remove it by date x/y/z or it gets donated to Goodwill or whatever charity runs a pick up service in your area. And I'd probably keep some pictures.
What you don't want is for ex to reappear in 45 days looking for her $ 6000 fine leather sofa you agreed to store for her until she could get it into her new digs --------
You are into a can of worms where there is a bailment created even if its a bit involuntary on your side and you have some level of duty to care for the stuff until it is picked up or you clearly go thru the steps to establish it as abandoned property --and those often are long steps if you follow the official rulebook.
Just a lay suggestion--a solid track record of notice(S) to come get it or it goes to charity is probably good to have....
One alternate view is that if she made a gift to you of the sofa a while ago then its now yours to dispose of as you please.
But be careful not to argue both ways at the same time .
That does not rule out you send her a couple of notes to confirm that the correct status of the sofa is she gifted it to you back about September.....