My husband is cheating on me and want to know his password to his Facebook account?

You distrustful POS!!! The both of you probably.

I will only advise you not to do it.. The more you want to know, the more sadness you will get and it may break your home.. Just keep telling him "____ you know I love you and you know I will be hurt when I find out you're cheating on me"...
Men always thinks a lot. And with such words, it comes ringing always in our mind even if we are about to sleep with another lady.. Just try that and you are a smile on tour face but don't hack for anything

If you know that your husband is cheating on you already, what good can come from having access to his Facebook account? The information that you are already privy to should be enough for you to come to a decision as to whether or not you want to continue with your marriage. 

Ultimately, it may be time to address the issue with him and let him know that you are in the know.

The most important thing is to ask yourself one question - What do you want? Do you want to stay married to this man and build a future with him? 

If so, playing the role of detective may not aid and abet the outcome, but only serve to hurt you and hinder the process. If you love him and you want to stay with him, it is best to discuss what you're going through and potentially seek marriage counselling to resolve your issues. Violating his trust won't make up for his violation of yours.

If you can not accept his infidelity and wish to file for divorce, it's best that you make your feelings clear as soon as possible and go on the hunt for a good divorce attorney. The messier it gets, the harder it will be for you to overcome, so my advice is to proceed in the smoothest and cleanest way possible.

I hope this helps.