G.D.
This is a tough situation. My daughter is recently afraid of going/being upstairs by herself. She use to go upstairs and change numerous times a day. Now I can't even come down when she's asleep incase she wakes up...I do anyway and she gets very upset with me for it.
I think it has to be a combination of the two-tough love and comfort.
I would let her know she was loved, cared for, and safe. I would comfort her a little and then leave the room when I put her down. I've had to let my daughter cry it out many times. Sense she was 9 months she could climb out of her crib and would clear the middle shelf of her changing table and sleep there.
But I let her cry herself to sleep. She now mainly does very good going to sleep on her own when we do it that way.
It's important not to let them control our lives to an extreme and we need our own space and time for the benefit of everyone. But they also need to know we love and care for them. That they can trust us and know we're always here for them.
Well, I've been interupted a few time during this so I hope it all makes sense and helps you out a bit.