If you are consistently helping out as much as you can and still getting flack in that manner, I would look to the emotion behind the complaint. When she says, “I can’t maintain this place all by myself", she’s saying she feels isolated and alone with it. Is she still doing all the managing of it? If you’re only doing what is asked and looking to her to make all the decisions you’ve basically burdened her with the responsibility of success or failure of the family and taken on the role of an employee. That’s incredibly isolating. I’d ask myself why she feels this way.

Also, it may be that the things you are doing aren’t actually taking anything off her plate that’s overwhelming her or is acting to actually undermine her or pile more on. It’s great that you’re making sure the kids are doing their homework but does that go against her efforts in conjunction with their teachers to work on focus and consequences? Did you ask? It’s great that you’ve got them cleaning out the garage, but did you pull them away from their rooms they were supposed to be cleaning at her request to do it, leaving her to clean up after them, again? Are you making so much noise that it’s interrupting a conference call she needs to do for work? Did you ask?

Parenting isn’t a competition and it shouldn’t be a hierarchy structure either. To be successful and not wreck your relationship in the process you have to work in tandem.