If you have a joint tenancy ( and it sounds as tho you do ) then each party as a result of the jointure is liable for the whole debt.
so at the end of all this each of you should have paid a third. You should be able to agree on that one. So REALLY it is a question of cash flow.Once she agrees that costs should in the long term be a third then you can follow up with "fine - that means you cant behave in a way that causes us loss and not yourself"
Is the tenancy agreement the only document you have or have you all agreed another one between yourselves?
You could point out for a start that she has taken advice from her landlord how to end a tenancy and he understandably has given advice which will ensure his rent and unity of the deposit and as such may not be accurate.
You could ask her which part of the tenancy agreement is she relying on to give one months notice to you ? otherwise it is two. and yes as a joint tenant she is liable for all the terms. I cant imagine she will agree with that one having dealt with a lot of tenants
You should make sure she cant withdraw 'her' money from the joint account.
For the deposit - I would say - do we hold your deposit or does the landlord ( answer the landlord) well you are gonna have to wait as we will, for the deposit to be returned from him. - however it looks as tho she is already planning to off-set the deposit against her notional rent.
messy - it is not a question of what money but more when money.
I bet you will start quarreling about damage and deposits and when it was done and "it wasnt done by me but after I left, so I'm not gonna pay"
so basically it is about cash-flow
and the leavers attitude is gonna be ' I am not gonna have cash-flow probelms, you are "
I dont do joint tenancies but have a lead holder and say the lead holder is reliable for all costs and the others can go hang. The other thing for your next tenancy is to agree a break-up procedure - it is obvious that you and your frenz need one.
Difficult - sorry it has gone tots up like this
You will notice there isnt much law in this but a lot of
lets try to be sensible and get out of this with minimum but equal loss.