I too have suffered with HA for years. CBT really helped, as did the book on Overcoming HA mentioned on other HA threads. I understand everything you say Crazie, particularly the bit about children, wanting to be around for them etc. As my husband pointed out to me - which hit a nerve - I don't have to be around for them, if anything happened they would be looked after, they are happy, they would cope.... living life with a constant fear and wasting time with them now is very sad and missing out on the joyous side of being a mum. For me, different things have set the HA off - now, being pregnant, hormones have made it significantly worse, but prior to that, I feel I had really conquered a lot of it.
I agree with keekee in that if you google you will find sites which won't help. You need to be OK with being exposed to things (the CBT counsellor told me it was important to be able to see something on TV or read about something because if you AVOID issues, the fear heightens. I find this very true.) But some sites which are to so-call help you, seem to just talk about various health worries which might initially offer some reassurance but this very quickly disappears.
The most valuable advice is from others who have/are going through HA issues and finding ways to combat it, move on in life etc. I started writing a book about my experiences and what has really helped me (unfortunately shelved at the moment due to pregnancy and too much going on) which I really hope to go back to in 2013. I feel as though I have experienced the harsh reality of living with HA and 2 years ago decided that enough was enough. Coincidentally a move to another country, some time therefore out of work and space to really address the issues, was how my thoughts ended up on paper.
I had tried various general counselling, CBT, and medication - all of which helped at different times but I really feel that I moved on significantly by using many tools - and a period of 'cold turkey' for want of a better word, which meant taking away all the reassurance methods - doctor, asking husband to 'check' etc - and coming through this on my own. It was incredibly hard but surprisingly quick to come through and I did this whilst reading the 'Overcoming HA' book from the series which rang so many bells as I read it. I couldn't believe it, it was as though somebody had opened up my brain and read exactly what was going on!
For me personally, I knew WHY I had ended up this way. I ticked almost all of the boxes in the book and that gave me some comfort; I wasn't going mad! But you do need then some clear strategies on what to do when you go down the familiar paths of worry.
Certainly you need support in the initial instance but going to a GP needs to be because you are going to talk about HA and not 'can you just check this while I am here' because the root is not about these worries, but rather the anxiety. It's a reason why medication can help, to lower some of the anxiety which may put you in a better place to tackle the issues. And I say this as somebody who worked for many years in the field of therapy! In other words, getting medical help is not a weakness, but can help to work hand in hand with talking therapies.
Finally, for me, I found that sport was a big help. I took up running - not possible now being at the end of pregnancy - and putting on an ipod, plugging into some music, going off for a brisk walk, jog, run, exerting yourself and getting those really good hormones to come to the surface, in my opinion is a really useful tool.
Good Luck.