Yes ... it will end. What you need to do at the moment is ask yourself "How do I make this horrible situation as good as it can be?" That means asking:
(1) Is there anything that can be done with the relationship with your W? If she is really adamant about divorce then the answer is probably, No. But you do need, if you can, to try to understand what has led her to this situation where she feels there is no future in your relationship: for your own future good if nothing else.
(2) How do you look after your son? How do you look after your relationship with him? Whatever happens, he needs you and you need him ... and that means establishing a working agreement with your W about parenting him. Presumably the separation has helped with this, but you need to keep it in focus.
(3) How do you look after yourself, in the short term? It's not a question of looking after your long term romantic/erotic needs: that will take time, and it would be surprising if you felt now that you wanted to start dating other women. You have to grieve. But you need support in your grief; you need supportive friends, things to do, a way of life that suits you and supports you. You are entitled to be a little selfish about this: your W wants you to lead separate lives; if that is what is going to happen, you can at least make your life as good as it can be. There's no call for being vindictive, but you are entitled to look after yourself. If part of the deal of marriage is that you look out for each other's emotional needs, part of the deal of divorce is that you dont.
(4) How do you look after yourself in the long term? That means, I think, trying to work out what you can learn from this failed relationship, what you take out of it (the positive, the years of happiness, your son) and the negative. It means above all forgiveness and reconciliation.
Just a word about that. You are going to have a lot of forgiveness to do: forgiving your wife, but also (I suspect) forgiving yourself for your failure. And reconciling yourself: to your own character, to what has happened to you, and to your wife. I don't mean "reconciliation" in the sense of "getting back together", I mean it in the sense of learning to accept yourself and her and what has happened to you for who you are, avoiding a bitterness that will sour your whole life.
Don't expect forgiveness and reconciliation to be quick. You have to feel them, not say them. That means acknowledging your hurt, your anger, your incomprehension, maybe your disgust. Weirdly, it probably means letting go of the love you feel for your wife, but which you have to accept she doesn't feel for you (and, I know only too well, that is a hard, hard, feeling: I've been there). It means naming and facing these demons, because we cannot forgive what we cannot acknowledge.
A few practical suggestions. If you are religious, consider seeing a priest or a pastor, asking to talk with him or her, and asking to pray together for reconciliation and forgiveness with God. If you are protestant, you might find this a rather alien idea, but the protestant tradition like all religious traditions acknowledges the cleansing value of openly acknowledging our sins. If you are not religious, consider talking to a counsellor, but try also to find some concrete and symbolic way to "let go" of the things that trouble you: write them on a piece of paper and burn it, for instance, when you feel you are ready to let these things go.
God give you grace to change the things you can, to accept the things you can't, and to know the difference.
