Hello Heather.. If I help you, will you send this home sick Brit some Chocolate Bourbon Biscuits ?
Unfortunately you can not process this divorce in the UK, it has to be in the US. If your US husband also wants the divorce then things will be a lot easier. If there are no kids or property, it should be fairly easy.
The best action would be for your husband to file the divorce.. is this an option ?
Also make sure the INS is aware that your application for residence is cancelled otherwise you will have problems if you ever wish to return to the US on vacation.