OP, I will start by saying I do not condone affairs, regardless of circumstances.
However as with posters above it sounds as though both of you checked out of this relationship in all meaningful sense years ago.
As far as the work issue goes - while it is possible your OH is trying to shift blame, or get his ducks in order, and whether your lifestyle is normal or agreed upon or not, in some ways none of that matters.
You've come to a point where both of you are are trying to make the relationship work going forward. He definitely has changes to make, given the affair. But he is also clearly telling you that he is no longer happy with the current arrangements.
You can refuse to make any changes "because he was in the wrong", and because everyone else does it, and because you are happy with the current set-up. But how long will the relationship last if you do this?
You either take on board his thoughts and position, and both try to make things work going forward - which will almost certainly require you to have more practical input into the house/a part-time job going forward.
Or your relationship doesn't have long left (which is also a very real possibility anyway - a 4.5 year affair is no small thing at all, and it sounds as though he is not getting much from the relationship).
In which case you would also be wise to look at getting a job, I believe. Only you know whether his earnings are high enough that you would get enough from a divorce/maintenance to continue to fund your lifestyle. If they're not, you're going to need to work - and if this is the case it's better you start now before you are left high and dry, and while you are still able to pick a job that will work well for you, rather than grab the first thing that comes along out of necessity.
So from a practical point of view, I can't see it being likely that you will be able to maintain your current lifestyle without getting a part-time job, or doing more around the house.
I would personally look at a job - at least that way you would be in a better stead to support yourself if/when it came to it.