DH is ready to kick Eric out over all of it
Danismom, I think that you should let him do this. Guys have a different way of viewing things sometimes. If DH is that fed up perhaps you should just let him deal with it. It will be much less stress and work for you in the long term.
If things get even worse after you let Eric stay your husband may blame you for his continued presence. If DH will actually get rid of him now - count your blessings.
I agree with the others. If Eric and Tammy are both working, and paying nothing for Tammy and Dane to stay with Grandma, they should have plenty of money to find their own place, even if Tammy and Dane stay with Grandma and move at the end of the school year. They'll also have a place to stay when Tammy and Dane visit Eric during school vacations.
Let DH push him out of the nest to fly on his own. You need to do it before he and Tammy up their expenses to meet their current income without paying for housing. If they get too comfortable with a two-income-no-expenses lifestyle, they'll keep imposing and expect a free ride. After all, isn't that easier for them?
i think that since Eric is Danisdad's friend, and Danisdad has already said that he wants Eric out, Danismom should support him in that decision. i'll bet $5 that after Danisdad's mom graciously rearranged things and invited Eric's family for Thanksgiving dinner, that Eric and Tammy sat on their butts at mom's house. they never offered to help, they never paid attention to their kid, and they really enjoyed their free meal. so in essence, in one week-end, Danisdad watched his wife AND his mother being treated as the paid help. he's done. good for him.
i know PPs said that Danisdad should sit Eric down and explain how things need to be. i don't see a point to that. Eric is used to being taken care of completely from living with his MIL. he never has to lift a finger, nor does Tammy. MIL cooks, cleans, and raises Dane. Eric and Tammy are used to having someone else attend to all of their needs. that's not going to change, until the change is forced.
the Danis are not taking Eric and Tammy to raise. Eric needs to be informed that it is time for him to find his own place. he's used to living with his MIL for free; there is no reason to expect that with the nominal amount of rent he is giving the Danis that he'll suddenly grow up and be responsible. heck, for all we know, in his mind (and Tammy's) that nominal amount of rent basically entitles him to full catering and maid service as one would find in a hotel.
this isn't going to get better. in fact, it has the potential to get a lot worse. can't wait until Christmas at the Danis if Eric, Tammy, and Dane are in residence. after all, they "can't afford to give Dane a good Christmas." wouldn't surprise me in the least if, in addition to expecting the Danis to cook for Dane, babysit Dane, and cater to their every whim, they aren't expected to buy Dane gifts to compensate for the fact that Eric and Tammy can't afford said good Christmas.
Danismom, listen to your husband. support him in his decision to ask Eric to leave. you did the best you could. you tried. you unfortunately took a gimmepig into your home, not an adult. cut him loose. now.
cut it off now. Danisdad needs to let Eric know that he needs to be out in the next 6 weeks. and that Tammy and Dane will NOT be coming to their house for Dane's Christmas break.