It doesn’t work. Fighting depression. Resisting sadness. Trying to be happy at all times and in every situation is not realistic or healthy. Grief is an essential part of human emotion process. We tell ourselves and others, “Don’t be sad.” “Look for the positive.” 
Sadness is not failure. Sadness can actually help us to appropriately come to terms with loss. Depression is often prolonged because we fight sadness with all that is in us. We resist and we strain and we try so hard to avoid sadness because we are trying to avoid pain.
Believe it or not, it is necessary to grieve. We will grieve eventually. It will not be denied. Those who believe that they have gotten away with avoiding grief don’t realize that the hardness of heart they now carry is robbing them of true relationship with those who need them to be open and honest and vulnerable. 
When you turn off and deny unpleasant emotions you inhibit your emotional health and eventually physical health. We often avoid sadness with anger, with humor, with addiction, or any number of other distractions. The toll it takes eventually becomes unbearable and we have meltdowns and we lash out and we cause pain to not only ourselves but those we love.
When you feel sad or melancholy give yourself permission to be sad for awhile. Feel the emotions instead suppressing them. Deal with what they bring up.
Cry if you need to. Tears actually help release pain. Give those around you some time to feel sad sometimes. When we release pain it allows us to begin to heal. Our God is a comforter. His Spirit will sit with you in your sadness and He will not rush you. As you allow yourself to feel what you really feel he will not pressure to “get over it.” He will help you get through it and will be with you each step of the way.
People who realize the truth that emotions are God given and serve a spiritual purpose are healthier and free to lay their baggage at the foot of our Lord.
Take your sadness to our Heavenly Father and rest in His healing presence.

Yes, Christians are dead to sin.
Stop obsessing over it.

Romans 6:5-11 ‚ÄúSince we have been united with him in his death, we will also be raised to life as he was. 6 We know that our old sinful selves were crucified with Christ so that sin might lose its power in our lives. We are no longer slaves to sin. 7 For when we died with Christ we were set free from the power of sin. 8 And since we died with Christ, we know we will also live with him. 9 We are sure of this because Christ was raised from the dead, and he will never die again. Death no longer has any power over him. 10 When he died, he died once to break the power of sin. But now that he lives, he lives for the glory of God. 11 So you also should consider yourselves to be dead to the power of sin and alive to God through Christ Jesus. 
Since you are forgiven, walk in it the grace and beauty of what you have received. 

Receive His mercy and become what you have received. (walk in it.) 

Receive His love and become what you have received (walk in it.)

Under the law I forgive, to be forgiven. Under Grace I forgive, because I am forgiven.