If I'd had a crystal ball 25 years ago I would have opted for IT instead of nursing. Just because at the present time it seems like if you have excellent computer know-how there seems to be limitless potential - as well as good prospects of working from home and earning a fairly good wage.
Having said that, having been a nurse for 25 years it has been an epic journey of discovery - both of people, medical knowledge, technology advances and most of all myself. It's a career where you never stop learning, you never stop being amazed. On the other hand it can be the most stressful, dis-heartening and most impossible job on the planet. As to having the stomach for it. I honestly wouldn't worry, most doctors and nurses have something that makes them turn green. For me it was bones - the thought of a fracture made me ill! Yet I could watch someone getting their gall bladder removed or a huge wound stitched and it wouldn't bother me at all.
What I would say about nursing now is that I think it is a more exciting career than it ever used to be. Once you get one to three years post training experience there are endless exciting opportunities such as becoming a nurse specialist, health visitor and so on. Many of these posts are part time and pay well. I know that within the UK at least, there are many nursing posts within hospitals and community facilities that are part time and would allow you to do other things. At forty-two your still young enough to have a great career.