They do indeed think I didn't want them anymore, basically I was given a chance to go back home and work at things but only if I agreed to never ever see the baby from the affair and I couldn't do that so they all think I choose the baby over them all, I have no contact with any of my 3 children and that's what makes it so hard to function every day, I try my hardest to just get on with things and give my all to the 16 month old but part of me is already dead without my other 3 and I just have zero energy and can't be arsed anymore.
That's an impossible ultimatum you were given. Can you write them letters? I don't know how old they are. Ex needs to not intercept It as it sounds like she's alienating them. A letter for them each would give you the chance to express your love and commitment.
My ex left me and my son. It took time for me to come round although I never ever used little one against him. Anger does go in the end and I hope your Ex comes round. She is without question influencing the kids' view of you and their view of your love for them.
I learnt that you have to use the nice approach even if you want to punch them in the face. Could you write to your Ex also. Tell her how sorry you are for the hurt in a confident non grovelling but sincere way. Explain how much you want to see your children. Make it as nice as possible but be assertive. She probably wants to punish you indefinitely for this so you have to play the game.
I know when you feel so low it's hard to find the strength. I know your kids will love you they are just angry. If the nice approach does not work then threaten action if you have the strength. I wouldn't pull that card until you've exhausted all options.
You had an affair, so what. People do much worse and she will have to just get over it. Stop punishing yourself. There is so much hope there, you just may have to play the long game.
I think the letters are definitely the best option at the moment. Hope there is a way of getting them to the children / they are old enough to read them.