How can I improve on being faithful and stop lusting after other women?

You make a choice. You already KNOW what you risk if you pursue the other woman, or any other woman for that matter.

You DECIDE if you want to risk it all for that thrill, to risk losing that "perfect family", OR you decide you want to work on fixing whatever it is that you believe is wrong within yourself, so that doesn't happen again.

Like I said its a CHOICE. So, what do you choose? 

It's fine to think about it just don't act upon it man. 

Find a device to shock your self when you find yourself lusting over other women. Don't jeopardize losing what is valuable to you for something that is cheap. It's a mind temptation you must not let get in the way. If you make your lustful thoughts become reality you are going to regret it. 

Nobody ever said you're not allowed to lust after other women.  Or other men, for that matter, because I don't judge.  You just can't do it.  The law (legislated, religious, social / moral) doesn't say you can't think about it, it just says you can't do it.  Everyone thinks about it.

I've been faithfully married for over 20 years, and I think about other women every single day.  The girl at the store where I buy cigarettes, the girl at the fast food drive-thru, several dozen girls where I work... they all make eye contact and smile, and I think decidedly unholy thoughts about them all the time.  But would I ever do anything with them?  No.  I might think about it, but I won't do it.

My wife is in the same situation, only she has the advantage of being a woman.  Women have sex with whoever they want, but guys only have sex with whoever they can.  

I don't know the answer.  But if you do find out how to not feel lustful thoughts about other women please let ME know.  Life would be so much easier.

The other day my husband told me a co-worker showed him a picture of a woman on his phone and said she was available. Actually what he said was Do you want some pussy. 

This woman is married and apparently bangs other guys whenever and wherever as long as she gets gas money. 

My husband said he’s happy at home and why would he risk losing everything he had for a piece of ***. 

Lusting in your mind is one thing. Acting on it has, as you very well know, painful consequences. Replace your lustful thoughts with productive ones, focus your lust on your wife, and remind yourself that if you don’t change your behavior, you will have a lifetime of regret for being so selfish and thoughtless. 

Seems you’re possibly a sex addict, and you should seek professional counseling. There are also twelve step groups out there to help.

If I had to be straightforward, I would ask God for forgiveness and pray. Praying is meditation which helps reduce stress, promotes emotional health, self awareness and fight addictions (especially lust). Praying will help you become the best version of yourself and help your well-being. Like you said, you have a beautiful woman who loves and respects you. You will not lose another marriage but instead thrive a healthy relationship :)