20 months is a very very long time to allow this to go on....

Sometimes tough love is needed.

You need to have a sit down face to face discussion with her and start it out with a "we are going to be grown ups and there will be no yelling cursing and no nonsense"
( prior to this make a list of the things that HAVE to be changed no matter what)

There is no reason that after 20 months she has been unable to get even a part time job, might not be something she likes but hey asking " do you want fries with that" is at least something.

Explain that you will no longer allow your home to be jam packed with so much stuff. It will and has to be cleaned up by X date.

I would explain to her and how her money is being spent and that is she is unable budget her money to last the month that you will sit down and explain to her. and even offer to take her money and keep it safe and allow her X amount each week. If she resists, make it clear in simple clear english that things are going to change, You wont let the children go hungry but you will limit the amount of food she can eat. Sounds severe I know, But she needs a wake up call.

I would make it very clear her cursing and tantrums are going to stop right here and now.

I would give all this a deadline 1 month 2 months? and you will have to follow through or X is going to happen, IE Child protective services will be called. ( Yep super hard for you to do , but really do you want more and more months or years of doing pretty much anything for her??

She will mostly likely explode about all of this, So what, Tomorrow sit her down and go back over the list, and do so until she finally relents and starts helping HERSELF or the time limit has come and gone and you can call dcf and offer to keep the children but that she must leave the home.

If you don't put your foot down and force change well then your just enabling her to continue this abuse of your kindness.

Take back your home, But you need to really stick to your time limits on her completing the tasks.

If shes not working there is no reason for her to not have the rooms clean. Can you disable your internet while your not home? Change the password? No internet shes going to have time to get off her backside and do something. If she still refuses , I would get some large black trash bags and calmly tell her she can have the rooms cleaned by tomorrow or you will do it yourself and throw out anything you see fit to do and actually start doing it.

Time to just take control, all the way. No matter how its going to hurt.

I hope that thinks improve and you can have your own life back

Welcome to PC