Deeper Debts Than Money

So I know a couple at work that just got divorced, Him and Her, and I happen to be friends with both of them. They both used to be alcoholics, but they've been sober for about ten years. But. I know from casual conversation that He has started drinking again. I have no idea to what extent, and I don't know how much He drank to begin with. I also know that She thinks He's not drinking.

Now, normally I wouldn't say anything, because it's His right to screw up His life, but He's taking care of their 5-year-old Daughter several days a week, so I'm conflicted.

I think I should tell Her.

Any thoughts on the blog-o-sphere?