Eddie, best wishes for your wife and you. Our family has been through it. My wife, due to health issues (but not cancer) can no longer effectively care for the six that we have but will not consider "getting rid of any". I guess I should take comfort that we only have six and not the thirteen we used to have. Anyway, I agree with what has been mentioned already. Look for a reputable rescue group to take them. The operative word here is reputable because not all are.
I also agree that now is not the time. Bite the bullet until you wife is on the mend then have an heart to heart talk with her.
As for the biting, I follow the "three second rule". If a horse mouths me, I slam him in the chest within three seconds if possible. After that, they won't necessarily know why you hit them. I try not to hit them in the mouth because that can make them shy of other mouth related necessities such as worming or inserting a bit. That said, I will if the infraction merits it. While most of the mouthing is just part of wanting to be the boss, horses can do some serious damage including ripping off one of your arms.
The bullying behavior is normal though annoying. It can also be dangerous should a bully provoke another horse into reacting and running you over. Not sure how you feed but the bullies should be confined if possible while feeding.