You will get your energy back. You really will. You've spent a year living with someone who has no morals, who lied continuously, who cheated on you, gaslit you, coerced you, treating you in such a vile, cruel way. And now you've found out the truth and it's life-changing stuff. There's no wonder you're feeling drained by it all.
But you are in a better place than before you found out. Now you have the truth (or enough of the truth to know he needs to be gone for good). You know why you were feeling uncertain all along. You know you were with someone who didn't deserve you. You also know that you gave him another chance and he proved he didn't deserve it.
So you now know the only way forward is without him. You will rebuilf yourself. You will build a lovely life for you and your child. Lean on the good people around you. Seek professional advice. Don't confide in him or tell him your plans any more - he's proved he is not your friend. He doesn't act in your best interests. He acts in his own, which are often the opposite of what's right for you.
If you need to - fake it til you make it. When you're on your own, be kind to yourself. Allow yourself to cry. Eat your favourite food and watch your favourite films. Take care of yourself, mind and body. Build yourself up if you have to see him. Then treat him like an irrelevance. Someone you're not really interested in either way.
It will get better, I promise. Better things await you. And you can move forward living in truth, which is worth so much.