Hi hon
I came off citalopram a couple of years ago and for me the physical symptoms of withdrawal were exactly like how I felt when I started taking them. It was like I was developing a cold but never got to the green-snotty stage, bizarrely enough; I felt bunged up and it was hard to think clearly, but that resolved itself after a week.
As for the emotional side: when I went on citalopram, I didn't feel much difference for a few weeks and then it gradually got a bit easier to cope. I did notice, though, that I had to make an effort to change my ways of thinking (e.g stop having arguments with people in my head, try and apply CBT rules rather than assuming everyone thinks the worst of me, try to identify trains of thought that leave me feeling crap and deliberately not pursue them). If I didn't impose that mental discipline, the pills didn't help much. IMO, pills give you a bit of mental breathing space when you're feeling terrible - they give you time to develop coping strategies and let you keep your head above water. However, they don't solve the whole issue by themselves.
To me it sounds like you're experiencing some purely physical withdrawal symptoms (headache) and some physical ones which translate into emotional ones (hormonal upheaval making you feel weepy). I wouldn't think of it as the depression coming back, more of a temporary physical state that you're anxious about (that anxiety is prob making you feel worse)!
My advice would be to SLOWLY taper your dose of citalopram, as coming off it is not always a smooth ride, but also to really try and work out some mental coping strategies too. Easier said than done I know. I bought a book on CBT, some of the techniques really helped me.
Sorry it's an essay but I do hope some of that helps. Hugs and good luck xx