Re:Spousal Maintenance can I stop paying now?

Hello all
I wonder if anyone can give me some thoughts or experiences relevant to this situation.

I have been paying Spousal Maintenance and child maintenance for 12 years now, I have had no problem with this as the spirit of the court order was to keep my ex wife and the children in the matrimonial home, the spousal maintenance was the "top up" on top of the maintenance for the children to give an overall monthly total equal to the outgoings of the house and family (my ex-wife and the three kids).
Also at the court it was agreed that all the endowments on the house were signed over to my ex-wife along with the transfer of the house into my ex-wifes sole name.
I have always paid the maintenance for my three children and the spousal maintenance over these 12 years adding up to some £850 per month, this is less now as my eldest is 22 middle 20 and youngest 18, my real concern is now my ex-wife is cohabiting with her boyfriend and has been for the past two years.
I am still paying spousal maintenance at £400 per month and £150 per month for my youngest who is 18.
The terms of the court order say I have to pay spousal maintenance until she re-marries, I know she is co-habbiting
does co-habbiting count as marriage?
Does anyone think there is a way to stop paying this spousal maintenance as I am now heavily in debt and struggling to make ends meet at 50 years of age.

Cohabiting is difficult to define and isn't the same as remarriage. Do not stop paying according to terms of the order.In the case Ellis v Ellis it was said if Mr Ellis could not afford to pay he should have applied for a variation to the court order first and not just stop paying. Then he was sent to prison.

When there are substantial changes in financial circumstances the courts will take a fresh look at the situation and consider varying the amount of maintenance. Cohabiting is a substantial change and you could apply to court for a variation, although bear in mind variations can be downwards as well as up.