Since reaching out is still a possibility you might be considering, I would do it only as an offering to help in anyway you can, and that you'll be here for him if he needs, friend or otherwise.. that's what i'd say anyways

Obviously tweak it to suit how you most accurately feel.

But then leave it be. The point is to not use persuasive language and just let him know you're available . At least then he'll know has a support system in you. I'd assume he already knows, but personally I think it means more that you've shown him that, and said it.

Or.. you could ask for an explanation. Tell him you're confused and just want to know whats going on in an attempt that his explanation will provide clarification for your confusement and some relief for your pain.

However, this could backfire. First of all, he might not even want to. If he did, he would have told you from the start. Yet even an explanation does not gaurentee a better result for you. Especially if he's dead set in his ways while you're thinking you can change his mind. Of course, you could. But it's definitely a risk taking this route.

Also, if you do decide to do either of these things. I wouldn't suggest saying you know how he feels. While on the outside it may seem like he's taking the same course of actions as you did when you were depressed, it's likely he doesn't process the pain in the exact same way you did, and perhaps has different reasons for doing what he did.