Cuppa, I really hope somebody who's been through this successfully will visit your thread and give you some specifics. There are some wonderful advisers here, however my relationships aren't shining examples. Here's some of what I've learned anyway.
The problem isn't you. You're not "failing" to get over it, because you are the one who's been injured. If you'd broken your leg, would he say you were wrong to feel pain; would you be saying you didn't understand why you couldn't walk? He broke your relationship; he caused your pain. He needs to understand that and take responsibility for helping to mend his marriage.
Actually, it won't be so much mending your marriage, it'll be more like creating a new one. When a person has cheated and regrets it, they obviously feel shocked at what they've done and want things to get "back to normal" asap. I'm sure you did, too. The hard fact is, "normal" has now changed and there's no going back. The marriage you had was one where you trusted him more or less completely, and where he never imagined he'd do anything to cause you so much pain. It happened. Now, afterwards, you still love each other but it's impossible to feel as you did before - because, now, you both know stuff you didn't know before.
What you can do is build a new relationship between you, which can be even stronger for your new understanding of each other's weaknesses.
First, though, you BOTH need to heal the pain you're still suffering. If he loves you, he won't want to think of you hurting so much. One good start is to ask him for specific support, to help build your faith in him. If he's working all hours, he could phone you often - once an hour, four times a day, whatever helps you - just quickly for a chat, to let you know where he is & what he's doing, and to help you feel more connected. What else will help you? Do you need to organise more frequent dates together; has your sense of being a couple got eroded?
It's important to discuss your lives together in detail, and make plans for your future. What you want, your ambitions and dreams may have altered in the time you've been together. See if you can get a new excitement about the years to come. Maybe you'll even make a whole new set of plans.
There's lots more you can do - and he can do. You'll think of some for yourself, and other people may offer advice on what worked for them. Basically, you're not 'wrong' to feel on pins all the time - and he can do more to support you. I hope this works for you.
You might feel better for getting some counselling as well as getting your DH to work with you - not to help you "get over it", but to help clarify your feelings.