Dear Rosyn,
I was in the same dilemma as you. Best thing is to apply on your own merit having lived here long enough to gain citizenship provided you have qualified for the time period needed, which was what I did. If you lack qualifying period You could still apply as a spouse of a Bristish national but you would need to get your ex to fill in,and supply his passort details, marriage contract etc.
If you qualify eitherway, it shouldnt really be a problem which way you wan to apply. Just ensure that your ex will consent to supplying his passport copies etc. It will be much simpler for you if you apply as having lived here long enough, on your own merit.
You mentioned you have officially divorced? legally separated, is another legal agreement which should not apply to you. if you are divorced then you are divorced.
Hope this helps.