Really need help urgently re my application

I've been living in the UK for almost 10 years, I'm from Zimbabwe.

I married my wife 8 years who is an EEA National - last February I applied for a new 5 year stamp.

I received a letter from the home office yesterday saying that my application has been refused on the grounds that I have not proved that my wife was working for the last 6 months.

Me and my wife seperated last year and she has now moved back to Zimbabwe. We are not yet divorced but she is obviously now not excercising her treaty rights.

I informed the HO of the change of circumstances last October but they told me to carry on with the same application.

As I've now been refused but they've told me I can appeal through immigration and Asylum.

Do I have a right to remain in the UK on my own grounds?
Should I appeal?

I don't want to return to Zimbabwe so really need some advice as to what to do next please. The HO are being most unhelpful and just keep talling me that I shouldn't be hear - surely I can stay on my own grounds?