You have an awful lot on your plate with your father's illness. There's no need to feel like you have to make some decision right this moment.
Yes, your H was a jerk. He might be hopeless. But sometimes it is helpful to ask yourself, what would it take for you to trust him again? What behavior would that require? What would it look like?
If you can visualize that, then you can also communicate to him what you expect, and you have a yardstick against which you can measure the sincerity of his efforts.
In my case - when my H finally left - I realized that this time, after two prior affairs and one prior reconciliation, that there really wasn't anything he would be able to do that would ever allow me to trust him again. Once I realized that, it was easier for me to let go.
