My friend, you're being walked all over.
You can't get walked on unless you lay down.
When son-in-law and wife are going over plans, go in garage and say "Hey, I'd like to know about this since I'm paying for it!" Or "Hey, how about letting me in on this?" or "I may not understand all of this, but at least tell me what's going on." You DESERVE to be let in on the plans and whatever else they have up their sleeves!!! They haven't seen fit to advise you of anything so you're going to have to make SURE that you're informed of these plans!!! Communication is seriously lacking here, and that's not good.
You and wife would be well served by a therapist who deals with couples counseling. You two don't seem to be able to communicate. Actually there is an art to communicating, and you two need to learn how to do it. Right now, there doesn't seem to be ANY.
Do you think wife would agree to it? If she says no, then YOU could go to a therapist alone. It would do you some good -- you might learn how to express yourself a bit more emphatically.
Right now, you're not being heard, and perhaps the therapist could help you learn how to BE heard without insulting or offending anyone.
Just an idea. But I think it might work. I wish you the best, dear friend. Please take care, huh? Hope to talk to you soon. Hugs, Lee