If so, one year and a half after separating sounds like plenty of time, especially if your WAW has done the same thing long ago. I agree that it would be moot and perhaps a bit silly to contact her and say "I think we should date again."
I respect Starsky309's view, though my own is different. I think the other party, your WAW, has broken the contract and freed you from behaving as if you were in a relationship with her. In any contract, when the other party defaults, it frees you from your own commitment.
I don't entirely disagree Mozz, and I do agree that it's too late for him to have the "should we date others?" conversation. I would have urged him to have had clearer understandings with his wife heading into the separation.
I certainly wouldn't have asked her PERMISSION at this stage that they're at, but I probably would have given her the courtesy of a heads-up. In fact that's exactly what I did in my own sitch.