I wish you could make her snap back to reality. Now knowing the boyfriend's age and the way he lives, as well as having clarification about the ebb and flow of your family schedule, makes me a bit concerned that your wife has a distorted perspective, and is not "in love," but using the boyfriend as a "vacation" from her life.
I understand that people do this, but it only works when you say to yourself, "This is part of my life, and in order to keep it, I have to make sure I tend to the other parts of my life."
Sure, I could say, "Screw the cats. I'm tired of shoveling shit. I'm letting them all outside. They can catch rodents or birds if they want to eat. Or the neighbors might feed them. I gave the past X number of years of my life to the cats; if they didn't have me all that time they would be worse off than they are now. I'm done taking responsibility for the choices I made that put me where I am today. I have this cute guy with a big dick waiting for me, and we're going camping. See you when I see you, cats."
But I don't.
Instead, I say, "I'm going to take care of the cats and make sure they have everything they need before I go out with someone. Then I can relax and enjoy my time off, knowing that when I get home, the cats will be waiting for me and we'll be glad to see each other."
I would never think about running out to see my boyfriend and expect my husband to take care of the cats because I couldn't be bothered to do so. This is what is colloquially known as "Being a Grown-up and Taking Care of Your Grown-up Business™". If you want to act like a child, expect to be treated like one.