For the ethics component, I don't think the things you mentioned are a concern.
In my view, workers should be just as loyal to the companies as the companies are loyal to the workers. 50 years ago corporate loyalty meant pension plans for life, insurance for life, and contractually guaranteed partial plans if you were laid off, and workers were generally "company men", loyal for life. 30 years ago that meant companies giving heavy investments in retirement plans and good benefits, but nothing permanent with an expectation of a few months or perhaps a few weeks notice from either side. These days company loyalty means I'm loyal all the way up through payday, and I know I may be called into a layoff meeting because the corporate earnings call is next week.
Why were you offered another job? Were you looking for another job? Did they headhunt you? If you were actively looking for an exit strategy anyway then take it.
Are you happy there? If you find joy in your work you may discover the new workplace does not fill the same needs, leaving you better paid but unfulfilled. On the other side, if you aren't happy with the work you've got then a change may be good.
The fact that you don't think your current company will be there in a year is a major issue. While it can sometimes pay to be the last person in the office, usually it means getting burned. Having a good job lined up means you don't end up unemployed with an emergency job search, so that's a good reason by itself.
The extra 12K per year is good, and depending on your location on the globe that can be significant. But I'd wonder why the higher pay and better benefits? Is your current company that much below market? Have they not given promotions up at market rate? Is the new company more desperate?
But be careful, you could be walking into a bad situation where they're looking for an emergency person to do a Herculean task. Go in with your eyes open looking for issues. Sometimes good deals and offers are made out of desperation instead of the much better reason of the company actively growing and looking for talent.
If generally want to stay leave your company and are otherwise happy there, you might also consider another tactic. Without mentioning the job offer, tactfully ask your boss for a raise similar to what you expect at the other job, plus some extra as a buffer in case the company closes up within a year. Given wages and benefits, that may be 25K, or possibly higher, plus the additional time off. Be extremely careful about approaching it, the same as you would any other raise or increase. Do it in the morning, with mild trepidation, explain that a new project is coming up, you've got a new baby in the home, your wife is through maternity coverage, and you feel it would be fair given your needs, your past contributions, and your expected role on the new project. Make a case you think you're worth that much.
Just be careful not to mention the other job, and do not make it to be a threat. Giving in to demands while finding a replacement is a common tactic for companies, they'll dump you when they get the replacement. Let the boss think you have some good reasons for needing significantly more money, not that you're about to bolt.
Assuming you want to stay there and your current boss accepts the wage increase, congratulations, you'll be making more and staying where you are happy. If he says no or doesn't accept it well, that's another good reason to accept the new job offer.
