OK,
Besides kicking her to the curb (the best advice),
you could try a "Beaches" vacation. Diving included, lots of family and kid activities and "SHE" can sit on the beach and complain while you take in free diving. Diving included at no additional cost.
This reminds me of what a friend said at hunting camp one year about a complaining wife, "I can understand a young newly wed going through this, but a fully grown man?" No wonder she has an ex-husband, lucky bastard got out early.
On the mid-life thing, don;t let it get to you I’m 56 years old and hunt fish and dive like a teenager.