OP, I think you're getting a bit of a hard time on here from people who don't understand how all-consuming and exhausting anxiety can be. People saying things like "but if you do the school run and go to toddler groups you can get a job". That's not the case at all.
You may well be able to drag yourself out of the house and get the kids to school, but it might be a monumental effort and leave you exhausted. Toddler groups much the same (plus, you can LEAVE a toddler group early if you get anxious; in work you generally can't).
People saying "make more effort to go to work, push yourself into doing things you find uncomfortable" may not realise that you've used all your effort just to get out of the house, and that getting out of bed makes you uncomfortable.
You sound like you have very little confidence, which can easily happen if you spend many years looking after kids and just "surviving". It's almost understandable that you don't want to work, because that involves putting effort into a lot of other things that people take for granted - wearing decent clothes, doing make up, making small talk with colleagues etc (depending on the job obviously). Those can all be, individually, overwhelming to think about when you haven't done them for years.
But I think you'll find that dealing with your anxiety will help a lot with changing your attitude. It sounds like Citalopram isn't working brilliantly for you. There are other meds, and options like counselling. In your shoes I think step 1 is to get to the GP and discuss this. Explain that you need to get back to work, but your anxiety is making it too overwhelming. Ask whether you could be referred for counselling, or whether they think different medication would help more.
Do things to build your confidence. Some places allow you to volunteer on an ad-hoc basis, rather than committing to a certain time each week. Try that and you may discover skills you didn't know you had. It will also take your mind off yourself for a while, which will change how you think about things.
Try a simple mindfulness app (Headspace is good, but there are others), or look up relaxation exercises on YouTube.
You say you don't go to the supermarket. Try going some day. Not to do a big shop - just go in have a browse, maybe buy some milk. Keep doing it until you're just on auto-pilot and not even thinking about being anxious.
Basically do all you can to deal with the anxiety, and see where it leads. In a couple of months you might find yourself wanting to get a job, but even if you don't, you'll find it easier to make yourself do it. And it will show your DH that you're making effort.
Little changes will make a difference to your thought patterns, and that's a good step towards beating the anxiety.