Your husband may be discouraged, and he may even have turned his back on God - but God has not turned His back on him (or on you). God loves both of you just as much now as He did when times were easy - and once you realize this, it'll make a big difference in the way you live each day.
This is why the most important thing you can do is turn to Christ and ask Him to be the center of your lives - and your marriage. Perhaps you've never really known Him; perhaps you've only drifted away from Him. But whatever the past has been, start afresh by committing your lives to Jesus Christ and asking Him to help you during these difficult days.
Then commit your situation to Him. Ask Him to renew your relationship, and to help you to deal with each other in love, and not with anger or bickering. The Bible's words are for you: "Love is patient, love is kind.... It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs" (1 Corinthians 13:4-5). Don't let circumstances rule your life, but let Christ rule you and your circumstances by His Spirit.
In addition, pray together about the future. Perhaps God will open a new job for your husband; perhaps He'll lead him in a different path, such as job retraining. Be open to what God wants to do in your lives - and receive it with thanksgiving.