It is your home, your rules. Clarify your rules to her. If she will not respect your rules then she is disrespecting you. If she will not comply then turn her out. Don't lose sleep over someone who will not respect you in your own home.
You guys have put up with a lot of nonsense from her. As far as her helping you take care of your aquarium, line up a replacement. If it is an important activity to her, maybe she will turn the corner and come to understand that she must comply with your requirements of her. You are paying too high a price and too frequently for that infrequent convenience.
Draw a line with her and be clear to her about it. Your wife has fired one shot across her bow. Now may be the best time for the next one from you this time.
Good luck,
fab