Is this fair?

We rent from my mother in law. We have no formal rental agreement in place anymore and at this stage the relationship is more professional than anything else.

We pay a fair amount of rent considering we're also fixing the place... It's badly neglected.

She had a hissy fit last year, she expects to be paid a high rental amount AND for us to fix the place because we're living here (she's a full on narcissist). Anyway, we upped the rent by a couple more hundred bucks but that's all now. She's not going to get any increases this year at all because we did TWO last year after she threw her fit.

Anyway, we got a plumber out today for several issues that just couldn't be put off any longer. Unfortunately because of the lockdown, we didn't exactly have a whole lot of choice as to who to get in (as not everyone has their essential services certificate) and this plumber was a bit more expensive (substantially more expensive, actually, but we had no choice).

What we've decided to do this month then, is to pay the rental amount LESS the plumbing amount. Do you think that's fair enough? We really can't afford to pay the high rental amount PLUS a big plumbing bill (both our income has been horribly affected by COVID19).

Since we've been living here we've spent about 20k over and above our normal rental amount just on repairs and upgrades she refuses to fix, plus she's actually evading rental tax because she asked us to stop using the reference "RENT" when we pay to her.

***We have told her we'd sooner move out than pay literally every single thing she expects us to but she asked us to stay.

****She absolutely does take advantage of us, but she plays the "poor single mom, I did the best I could with my children and none of you talk to me anymore" card whenever my husband tells her he's done, we're moving out. He hasn't spoken to her since September.

*****This particular issue was a recurring blocked drain we have to get a plumber out for at least twice a year because she doesn't want to pay to have a tree by the drains removed (it's the roots causing the issue) and a pipe in the ceiling that rusted through three weeks ago. We've never taken off the blocked drain amount off our rent before.