Sounds to me like he is depressed - all of that inactivity and failure to make decisions or follow through are prime examples of depression. He's paralyzed, really - he can't make a decision about this company (and yes, red flags all over - he's going to get burned). I would speak to his doctor and get a referral for a counselor - one that will see you at first along with him, but one he sees on his own. He's 60 - that's not old! People aren't retiring until 70 or so anyway so he can certainly reinvent himself. He's using the computer as an excuse, he's using "dishonest sales people" as an excuse, "long hours" as an excuse. He may be emotionally unable to make a step further right now without counseling.
Yes, you need to stop enabling him. Work with your own counselor if you have to, to find the words and the motivation to tell him that what you're doing isn't working for either of you.
Stop doing his work for him - he can get a free job training class at the state employment office. They teach computer skills and things like that.
His failure to address his health needs makes things more expensive and more risky. I think his doctor and his pharmacist should have good info on his drug allergies so, short of making sure that everything is done at one pharmacy, back away.
Separate your finances. Really. Set up a bank account that does not grant him access. He can pay his bills, including his medical and his insurance, out of his own money. See a financial advisor - your tax preparation person should be able to refer you if you need help. The price you pay will be worth it.
You have to protect yourself. If you have to sell your house to get into something more affordable, do it. If you have to start selling off some possessions (antiques, heirlooms even), do it. It's hard but sometimes it's necessary.
It sounds like both of you are kind of worn out and want the other one to do everything. That's not going to work. But your problem is not really his job situation - it's the dynamic between you two, and the fears you both have that you just, understandably, want to go away. It sounds like you have a daily work ethic and he's too compromised right now. But overall this is a relationship issue and needs to be addressed that way, with some financial advice thrown in.
Good luck.