If he asks you to come back and you agree to do so, I would also take the opportunity to air out some of the problems from before - that it makes you uncomfortable to be told secrets and then expected to cover up for him. Assuming you knew his wife/girlfriend, that's pretty shady to dump that on you and expect you to lie for him, and you should be clear that going forward that's not acceptable.
And that you enjoy your job and work, you're responsible and hardworking, and if you come back you need to know that you can legitimately get sick without him getting an attitude about it.
And that you enjoy your job and work, you're responsible and hardworking, and if you come back you need to know that you can legitimately get sick without him getting an attitude about it.