True Love Hurts

Matt 10: 22You will be hated by everyone because of me, but the one who stands firm to the end will be saved.
What to do when you find your closest brother has committed the most egregious of sins?  As it states in Matt 18, you go to him and "if he listens, you have won him over."  I recall a particularly painful exchange right at a year and a half ago.  I ranted, but you had already repented.  Yet instead of being defensive and excusatory, you took it.  You took a fusillade of rants from someone you really didn't have to even discuss this matter with, perhaps because you sought forgiveness in your heart or knew you deserved it.  Regardless of why, your response was to repent to God and your wife and they have won you over.  A family has been saved because of your repentance and their forgiveness.  Thanks be to God who puts forgiveness in our hearts especially when we lack the capability to conjure it up on our own. 
I've been surprised at my own reaction to that event. I was (and still am today) absolutely in total state of disbelief that a man of your stature could fall and fail so completely.  Instead of standing in judgement of you, upon realizing your repentance and humility, I looked inward at my own culpability in this situation as well as my own susceptibility to sin like this and I've stood deeply convicted by my own shortcomings ever since.  In fact, I've taken a deep look and recognize that in reality I'm no better.  While not committed physical sin, the lust in my heart condemns me none-the-less.  I struggle to love my wife like Christ loves the church, even at times blaming her for "making it difficult."  As much as I pray, I cannot shake the sin that holds me.  I've prayed even to the point of tearfully begging God to simply wipe all desire from my heart except that to agape her, yet I remain a man way short of who I should be.  What a poor and wretched man I am! 
Others have responded very differently than you.  There is no repentance, even no admission of wrongdoing.  As I've wrestled with my own response, I've realized that Satan aims to clearly and cleanly attack in our blind spot.  That area of our lives where we refuse to yield Lordship to Christ.  That area where we think we're in charge of creating our own joy and happiness.  That area where we buy into the clear lie that "God helps those who help themselves."  Satan doesn't attack me with the temptation of homosexuality because I'm not blind to it, but he does attack me with lust because he knows although homosexuality isn't an issue, my sexual desires are not fully yielded to Christ.  So I struggle.  I struggle with my eating and drinking habits because I cannot fully yield to Christ.  Yes I pray.  Yes I want to be more disciplined, just not enough to substitute water for Diet Mtn Dew or an apple vice cookies.  I just refuse to yield, but I don't want the consequences of being old and fat.  You can look in from the outside with pity and know that I'm doing it to myself and it would be easy to change, but change from my perspective is beyond me.   
So those with whom you struggle must make a decision to own their sin.  Short of that, I'm afraid you're stuck.  You cannot yield to the lies of Satan that say to love we must accept sin.  That lie is killing the church today.  We are no different than any other social club because we've bought into the secular humanistic lie that love means acceptance of any and all decisions with no consequences.  This is in fact diametrically opposed to love.  Divorce wrecks families and the sins of the father run the deepest from this particular sin.  There is no honor, no integrity, no respect, and no agape lessons to be taught to our sons from this event.  Only the lesson that comes out is that we know better than God how to achieve our own happiness and that is far more important than holiness - a "yellow brick road" to a life and eternity of and in hell.  We see it in others and we are pained by it, yet we have no power over them to force them to repent.  Note that this is the power that God chooses to withhold over us.  We know he could force us to choose wisely, but he refrains.  His Holy Spirit within us, therefore cannot empower us to force others to choose wisely either.  
A lot of words to say, we're stuck.  I'm stuck with a Mother-in-law who is possessed by the demon of addiction and I have no answers.  Ultimately she must acknowledge and repent, then and only then can all the mighty power of God save her.  Similarly you're stuck.  You're brother is flying in 1v1 aerial combat.  His foe is in the sun and unseen, but a missile called "I can find love & contentment in disobedience" is inbound.  He is ignoring his radar warnings and calls for evasive maneuvers because he thinks "he's got this."  Like countless others before him, he will die at his own hands not out of heroic bravery, but out of foolish bravado.  Unfortunately, others will go down in flames with him. 
I've not told you a thing you didn't already know, nor have I helped one bit.  I only say it for two reasons 1) your humble response has clearly had an incredibly positive influence on at least me and my walk and I believe I'm not the only one, so God's promises are very real, my faith is increased, and for that I'm thankful (NOT the outcome I would have predicted 1.5 yrs ago!); and 2) there is but one Savior, we're not Him, but we know that one day EVERY knee will bow to Him.  I pray that he bows in this life as opposed to the next.  I really don't know what else to do.  Clearly ignoring the issue and pretending to love by showing "support" is not the answer to drive one to their knees.  In fact, to do so would enforce what we call "negative training"  - lessons that drag us away from God rather than point us to Him.   I wish I knew how to help at least you, if not him, but I do not.  I know God does know, but it all starts with him willing to own his sin.