I need to be able to see what my husband is emailing and his im
conversations on yahoo ,sge. We are not currently living together and
our computers are not networked. I need to know if he is being honest
with me and to do that I need to be able to see his email and his im
conversations. He uses yahoo msger. Also How can I see through the
stealth or the invisible setting on that messenger to see if he is
really online. Any help other than the suggestion of "if you need to
even ask you need to leave" would be appreciated.

I doubt that this would be legal.

Scriptor

it would certainly be unethical but there must be something that is legal..

If you are uncomfortable providing me the answer I need maybe you can
point me in the right direction to find it on my own. I really need to
discover the truth , I am talking about an 18 year marriage here and I
can't just toss it away on my hunches.

If you do you may end up with three choices: Alderson, Coleman, or Danbury.

http://www.cnn.com/2004/TECH/internet/10/07/internet.spyware.ap/index.html

1) You would have to access his computer to install software to
monitor what he's doing. About the only way to do that legally,
although still unethically, is if you own the computer you're
installing it on (and you're not breaking and entering to install it)
and you're monitoring either your employee or your children.

2) If you know his passwords you may be able to log into his email,
but IM is generally not archived anywhere - maybe yahoo does though.

3) The stealth feature is there for a reason.

4) The suggestion you mention, while harsh, may be correct. Perhaps
the two of you should see a counsellor

sorry
sparky4ca-ga

well, regarding your spoofing into anyone's e-mail a/c....
1. Its not ethical and legal in terms of information security and is
an offense under cyber law.
2. If still you want to access his Computer or e-mail then you need to
install physically a couple of network spoofing and monitoring s/w in
his machine.

And as per your second querry...to know whether your husband is in
stealth mode or is he deliberately trying to appear OFFLINE to you....
There is one way you can check it...n that is...Just check your Yahoo
mail a/c and click any mail which carries his e-mail ID with a
emoticon at start...if it appears GLOW...then he is online no matter
he has kept himself stealth for appearing offline.
i hope this helps....
Cheers!!!

Since you are married and depending on what state you live in, the
chances are that it is legal. That computer is actually joint property
while you are still married.

Things you can not do.. 
attempt to install this software remotely.
This is because you are doing this over your ISP and breaking the
terms of contract. This is illegal.

If you have physcial access, you can install Key-loggers(google
keylogger or key stroke loggers), Remote administration tools(pc
anywhere etc), and anything you
desire(http://www.l0t3k.org/security/), because the property is yours.
You can defend yourself in stating that you are monitoring your own
property. What if your husband is attempting to do illegal
activities.. You should know this. No different than installing a
security camera in your own house, as long as you dont lease/sublet
it. Once you install the software locally you can monitor it remotely
without breaking the terms of most ISP's contracts.

If your married its joint property.. unless you have a restraining
order or some other crazy ness.. check with a lawyer not google
answers.