Dog Separation Anxiety

So a few days ago a stray dog came into our yard. She’s the sweetest girl and we want to adopt her (if her previous owner doesn’t claim her), but it doesn’t look like she was raised well...she was in heat, had worms, was extremely dirty and malnourished. We cleaned her up, dewormed her and have been loving constantly on her but she has the worst separation anxiety. Any time my husband and I want to go out to dinner or grocery shop she howls and cries and scratches at the cage and I don’t know how to make her feel safer. We keep our shirts in the cage so she smells us, turn on the tv, cover the top and sides of the cage with a blanket but nothing is helping. I know it’s only been a few days but I feel so bad about leaving her that we keep putting off shopping and going on dates.

Any advice to help her anxiety?!