Sorry you had a bad day. I hope today will be better.
3 years ago I was in your position, it's raw, it's hard, it's frankly probably one of the worst times of your life.
All that you feel is normal.
I went back to my gp re lack of sleep and she gave me a second pack of sleeping tablets, but I only took one once or twice a week and then reduced to half a couple if times a week. I bought the herbal sleeping tablets from Boots and decaf vanilla tea and moved into that. It helped and gradually I could sleep again but it will take time. Not sure where you are but the heat at night at the moment is making sleep hard.
Feel the anger, feel the rage, let it all out. Do you have any friends you can meet to talk? In my view talking and letting it all out helps hugely as does a good cry.
Do you do any exercise? I did and found this a huge help, I used to do combat classes and imagine I was punching the hell out of them, still do on occasions! I ran and played loud music in my headphones.
You are not worthless, he was and is weak for doing what he did.
Don't believe the narrative of him not being happy, he probably wasn't but that is the only way he can justify doing what he did. Those of us that have been through this have all been fed that line. If he was that unhappy he should have told you, a marriage is between 2 people.
I had quite a bit of counselling which really helped me incase that is an option. I can recommend someone but I'm in Yorkshire so it depends where you are?
My ex had his dc but only for a 3rd of the time. He used a lot of his leave to go on holiday with her and just kept 2 weeks in the summer for the dc. I work full time and was left to sort the rest out. He didn't care, the OW was clearly her priority.
Interestingly this year he's taking more time off to be with the DC. Either he's realised or I hope maybe the shine is coming off their relationship!
So 3 years on I still have a lot of anger and hatred towards them and want her to cheat on him so he knows how it feels and for it all to have been a big mistake for him.
I want to go on to the happier and better life that others have said they have but I'm not there yet.
It takes time, so you are doing fine and all that you feel is normal.
Be kind to yourself and keep posting on here when you need to.