I used to have an awful fear of HIV. Sounds like you are suffering with GAD and Maybe OCD. 28 days is still too soon to see the full effect of the medicine. You should feel a small difference. If not maybe you need a higher dose or a different med. Talk to your doctor. But you also should practice some CBT and learn some techniques to help you live with the anxiety you have without it disrupting you life. I have had major breakdowns and they feel permanent but they are not. Trust me it gets better.
It really sounds like what you need is to get very serious about your mental health. We don't discuss hiv here, don't ask. But you need to become serious about psychiatric care. You're right. Your kids need you. Want to get better, take steps. Baby steps if you have to. Give your medication time, it takes 6 to 8 weeks and often they have to adjust the dose or add something or change something to get it just right. Takes a bit of time. Hang in there.
Who put you on the citalopram? How long have you been on it? If it's been over a couple of months, either you're not at a therapeutic dose or it's the wrong med for you and isn't working. Don't just stop, talk to your psychiatrist first, you need to taper off of it slowly if you choose to do that, but again, if the purpose of the med is to help tamp down the symptoms of your anxiety and you feel like this, it isn't working. As to your fear, I would ask, do you have a lot of irrational fears, do you have a lot of anxiety much of the time, and are there other things you avoid because of it? Or is this the only thing that bothers you this way? Medication won't necessarily help with a problem with just one phobia. It might, but it shouldn't be necessary to go on medication for one phobia. But if you have a lot of anxiety and your life isn't manageable at all, that's when medication becomes necessary sometimes. But whatever you do with meds, you need to find a psychologist who specializes in the treatment of anxiety and figure this out or learn how not to think this way. Meds can only tamp down your symptoms when they work, they don't cure mental illness. Your fears are pretty far-fetched, as you no doubt know, as you are basically at the point where you're believing people are out to kill you. Why would you think that? It's possible therefore that this is more than a phobia or anxiety problem, and another good reason to see a psychologist for a diagnosis. I would ask, did something happen just before you started thinking these thoughts that might have triggered such an irrational fear?