First, how do you know you're dealing with legalist? Well, there are some signs...
Basically (and I've said this before) if you take a look at Galatians 5 you'll get a list of what the flesh, under law, produces when it works hard.
But if you are led by the Spirit, you are not under the law. Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. Galatians 5:18-21
Take a careful look at this list, don't just read quickly over it. I still have some signs of these at times myself, and I can tell you it's connected to trying to be holy myself, by taking my eyes off Christ and looking at law and methods of change. When we were really deep into legalism and completely unaware that we were, our lives and marriage could be pretty easily characterized by sexual immorality , impurity, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions,and envy, to name a few!
Conversely, following this list you have the fruits of the Spirit (fruits NOT works!):
"But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law. And those who belong to Christ Jesus have crucified the flesh with its passions and desires." Galatians 5:22-24
The legalist lacks love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. Under law, all these good things were completely ellusive, we felt like God was dangling these delicious fruits in front of us all the time but we could never reach them.
Back to the dilemma, what to do with a legalist... First you have to really get a revelation of grace yourself, an ongoing revelation from the Holy Spirit. Then you need to rely on God to reveal his grace in the same way to your legalist, being open for him to use you in this process. This often look like responding to the legalist's sin with grace and love. As we receive grace, we can't help but let it spill over to those around us.
Really, this is usually a case of log and speck, if you know what I mean. When I find myself most frustrated with my husband's legalism, is when I'm most lacking grace myself. Slowly, sometimes painfully slowly, I'm learning that I can turn to God when I'm disappointed or impatient, or just plain hurt. I can march into the throne room of grace with confidence that I will receive mercy from my Father, I will be loved and he'll help me in exactly the way I need him to. Most of the time, I don't even know what I need, but he always does.
Our habit as women is to look to a man, our husband if we have one, and direct our desires to him as if he were God and able to fulfill and satisfy us. No man is sufficient for us , but God and his grace is! The more we experience God's all sufficient love for us, the more difficult it will be to offend or crush us and we'll be able to love our husbands (or anyone else)with God's supernatural love, the kind of love that softens and changes people, the kind of love that is constant whether you fail or succeed.
Does this mean we should overlook serious problems such as abuse? No, of course not, but as God reveals his heart to us more and more, we may be surprised at how we want to respond to people who are in serious sin.
We stop setting them up for failure by creating ultimatums and consequences, rules and regulations, by putting them under law. We begin to stop making accusations and start believing that there is truly hope and power for transformation , because we begin to believe the gospel! And at every turn the good news comes springing like living water from the depths of our being which is rooted in Christ, the resurrected Redeemer. Our words become life-giving instead of condemning and the power of the grace of God goes out to everyone we meet and sparks hope in them by his Holy Spirit. People who once joyously embraced salvation simply by faith but became enslaved to law again, prick up their hearts and ears and remember the joy of their salvation. They want to turn to God, they want to believe in Jesus again and turn from futile efforts of the flesh that always fall short. Together, we take the leap of all leaps of faith and let go all control over our own eternity and put every ounce of trust in God and his fatherly love that was demonstrated clearly once for all on the cross. And then, THEN, we will begin experience together transformations that are nothing short of miraculous...because with God NOTHING is impossible!