I have been comprimised

Long to short. A girl I have been seeing for close to ten years caused this problem. I got a spam message from several of her emails. It was BS about weight loss.

But where the problem comes in is a list of all her emails contacts comes through on the header. A number of people could decode the email handle(she talks about me to other people and one of my addys gives my real name).

My issue isn't to whine about this and how to help her to prevent her email from being spammed. BTW - she has both a Hotmail and a yahoo address. I have multiple addresses.

Not really
I doubt anyone going to spend the time to look at the header and try to figure out anything, most likely it's all going to people spam folder and getting deleted without being open,
most people don't open spam, not too much you're going to be able to do about it going to other people, whoever spoofing her email addressed already got the email list,

Don't use your real name when you use these addresses. Change your name in the email settings page.

Send her an email directly telling her her email account has been hijacked. Quite often, simply changing the email password will fix the issue. (I probably receive at least one if not more of these a week from folks with my hobby email in their books.)

You are totally right that if her hobby account has your personal email (not just your hobby mail) you potentially have been compromised. If someone contacts you, the simple explanation is your personal email is "out there" and many people (gawd knows who or how) are able to grab it for (gawd knows what reason)!

Ladies and Gents - the simple answer is DO NOT! NEVER! EVER! use your personal email or personal phone for hobby stuff. Doesn't matter what the cost of having a hobby email or hobby phone is; we simply cannot afford the consequences of getting outed by accident or on purpose.

If her contact list has been taken, no amount of her changing her password is going to help, the information is already gone, and may have already been sold many times over, for the most part they are just mining email addresses, don't make a shit who address it is, and they're hoping for three things, to send you spam or to infect you computer to get your contact list or both.
I'm sure if it was about someone gaining access to see her clients email info, you wouldn't of just gotten spam mail about weight loss,
Also do you know for sure that it was sent from her email, you can spoof email just like you can phone calls, all those addresses in the header could of just been random email addresses in the header, not from her contact list, also since she is a provider, and she most likely posts her email address anywhere/everywhere online it's easy to collect email addresses, heck there are programs that will strip out every exposed email address on a website.

No - these were legitimate addresses. Has her mother's, sister's email addy. And we don't have a provider/client status. I knew she was on seeking arrangement and has hooked up a couple of times. Part of our deal is disclosure and then follow appropriate safety functions. She has also, beside her family inadvertently outed a well known person. My question is - what can you do to protect from this happening? BTW - she changed all her passwords, but I agree - unless everyone changes their addy's, this is spilt milk.

Nothing you can do about it now, cow has already left the barn. like I said previously, the people sending the spam usually have three reasons to send it, and trying to find out if you're using providers, much less trying to find out who you are, unless they are identity thiefs wanting to place spyware on your computer, most likely isn't one of them.
Most people won't change their email address, they'll just send them to spam, and set up filters to send her email to trash, she may want to set up one just for family, one for work and one just for junk.
next time use a throw away email address, nothing that would trace back to your personal life
now if she's been contacting a terrorist cell somewhere, Homeland Security might come a knocking on your door
use all the tips given by all the other posters, it will save you worry in the future