Me [37/M] with my Fiance [30/f] of 4 years, I'm thinking of ending it.

Maybe it's just the quarantine talking, but we've lived together for a while now, both working from home. I feel like she spent the first few years of our relationship pretending to be what I wanted and after we got engaged she's slowly morphed into this entirely different person. Most of my issues revolve around the fact she is the least self-aware person I've ever met. She struggles with anxiety, depression, which I am always empathetic about. When she's in a low stage, she might lay in bed all day for 2 weeks solid, getting up to do a little work here and there. (We both have worked from home since before COVID) When she's in this phase I do EVERYTHING. I work full-time, cook dinner, do the dishes, wash & fold the laundry, put the laundry away, clean the cat boxes, vacuum, clean the bathroom, you get the idea. Usually by the end of the 2 weeks I will be getting burned out and I'll start letting the dishes go a few days, forget to fold the laundry. It all just starts getting to be too much.
I never say anything to her about it, I don't make her feel bad. I've been there with depression myself & grew up in a family where my mom struggled with these things. However, the second she starts to break out of her depression she'll do 1 or 2 chores and then act like like I do nothing. She's often very blunt and it comes off as very rude, barking orders like I haven't just been carrying the ship for 2 weeks or so. I usually let it roll off my back because trying to talk to her about it is absolutely pointless. As I said before she does not have any self-awareness. If you have issue with something she's done, she gets defensive and aggressive. If you even offer her advice on anything, even something small, she get's defensive.
It's gotten to the point where 50% of our conversations, which are becoming very rare at all, is her either saying something rude or me sticking up for myself out of sheer frustration. I was single for a while - I know how to take care of myself. I cook, clean, work hard, etc. She talks to me like I'm some 90's sitcom dad would would burn the house down if he had to do a load of laundry. As I mentioned before, my mom struggled with some of the same stuff and I was pretty much taking care of myself from the age of 13, including working and making my own money.
I own my home and I'm looking to get it on the market this summer. I bought it dirt cheap and have fixed it up over the last 10 years, I stand to sell it for at east 3x what I paid for it and we're looking at new houses. She's already making rules for the new house that I'll be paying for, like I'm going to let it go into disarray and do the opposite of what I did with my current home. For the last two weeks I can't stop myself from fantasizing about telling her that I'm going to buy a house and move and she's not invited to come with me. It makes me feel like an ******* but I just want to be happy.

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tl;dr: My fiance has turned into a miserable person and has no self-awareness of her own faults, but points out everyone else's. I want to sell my house and move without her.
EDIT: Thanks everyone for your thoughts, they are appreciated. I want to stress that the issue is not with her bouts of depression or those times where she doesn't contribute. I feel like she can work through those and she does contribute when she's not in that phase. The real issue I have is with how she speaks to me when she starts to come out of it. Not just a lack of gratitude for manning the helm but overly critical about the way I do things. and to be very clear, I have addressed that issue with her numerous times. Probably at the wrong times because it never seems to go well. Just wanted to add a little clarity as I see a lot of comments quoting the part "I never say anything about it" which is strictly in terms of her depression and withdrawal from every day life. That bothers me, but I try and encourage her and help her through those times.


Source.