The main explanation from my solicitor was that my ex-husband stayed and exercised the Treaty Rights in the UK for over 5 years so this applies to me now. Makes little sense to me because from what I can see, the only difference between EEA2 and EEA4 is the applicant's 5 year stay condition. There are no other specifically relevant details to my case. The only additional significant detail is that my ex-husband is being made redundant, which still doesn't make much difference to the form to be used.
Thank you very much, Tom