Most likely, nothing different will happen, but I'd say there is also absolutely nothing to lose if you did call her.

I would not even talk about the relationship or divorce. If you are comfortable, and your mutual friend wouldn't care, I'd say something like this.

"W, "mutual friend" told me you called her and you were crying. I understand how you are hurting and just wanted to let you know that I am here to listen should you need that. I have no expectations that you will need to, but just know that you can call me"

Something close to that, however you are comfortable and IF you are comfortable. I think this tells her two things. You are giving her the freedom to change her mind, and either way you feel for her.

You may not want to, and that's OK. There is nothing to lose now that doesn't already seem lost.