I'm so sorry you find yourself in this spot, but I'm glad you found us, MamaMia.
Your post will be seen by more members if it is posted in the Infidelity forum, so I will move it (and my response) there, with your permission. And put a link here for you to follow to it.
Your husband is having an emotional affair, at the very least. Most of us here have been on the receiving end of this nightmare, some have been unfaithful themselves. But
all of us understand what you are going through, and are here to help you through this, as others before us helped us. To do that, we need to ask a few questions:
1. You've been married for five years. How old are you?
And is this your first marriage?
2. Do you have children?
3. Is your husband this girl's boss?
3. Have you told anyone what's going on?
Do you have their support?
That should get us star
Now, for the immediate concern--
you:
Not surprising that you're not eating or sleeping. This happens to a lot of us when our world is rocked bysuch a betrayal. It is traumatic. It's so important to address these issues because you will need to be at you best to deal with this.
Make yourself eat something nutritious every day, even if you have to force yourself to do it. An egg, some fruit, some nuts--whatever you can. And lots of water. And see your doctor, who can help you through this time too. Tell him/her what's going on and that you are unable to eat or sleep. S/he can prescribe something as s/he sees fit.
Assuming you wish to save your marriage from this threat, it's important that you be strong enough to state clearly to your husband that you will not share him this way with any other woman. Try not to cry or yell, but to present a strong stance on this--cry when he's not around. I assure you, in his present state, your tears will not move him. (Ask me how I know.

)
That's enough for now. Others will be along said on, especially if we move your thread to the proper area.
Hang in there.