Bitterness is of the flesh, the sin nature. If your hubby is born again, he can exhibit either the fruit of his newborn human spirit listed in Galatians 5, or the fruit of the flesh including bitterness.
Whatever it is that you have done is irrelevant to his choice of which nature he allows to control his will. And the same goes for you.
When we are exhibiting love, peace, long suffering and the rest of Galatians 5, we are indicating that we are being controlled by our born again nature, our new man, inner man.
When trials come out way sometimes they are so severe that our reaction is to fall from our walking together in the newborn human spirit. We then trip others and back and forth. Our goal is to be controlled by the new nature so that we can be filled with the Holy Spirit. My counsel for you is to ask those elders in your life (spiritually mature Christians) to first address his inability to maintain his walk in Christ by exhibiting the fruits of his newborn human spirit. Once he has come into his senses and is allowing his will to be controlled by his new nature then you can address whatever it is that caused the bitterness.
I'm writing under the assumption that you both are born again and thus have that option to follow after either your new man or your old man.