I am appalled on your behalf OP. I've two sons also and am trying to imagine this scenario playing out one day. It's at first heartbreaking and then disgusting that they are showing you such disrespect. So at this point, that is what it is, you must now pull yourself together and get on with things for your own best interest.
In my opinion, you need to get the elder ungrateful son and wife out of your house asap. If you must, contact a solicitor to get your ducks in a row. Of course they won't be pleased but they are beyond disrespectful anyway so what do you really have to lose? And just maybe, it will make them look at you in a different light, as a woman who won't be pushed around and bullied by grown sons. Admitted or not, they'll respect that.
I think if you are able to manage this, the younger son may eventually come around. I can see what others have pointed out, that the older brother has essentially bullied the younger one also out of the house, leaving more for himself and wifee. The younger son may feel angry with you for basically laying down and allowing it all to happen. After all, what can he do? The older son is bullying his way into taking over and basically wiping the two of you out of the picture so he can have it all for himself. And he has no shame over it, no conscience at all.
You must hold your head up, stand tall and go forward in your own best interest. You can do this. I'll be thinking of you and wish you the very best.