God knows your heartache, and it isn't necessarily wrong to want to cast off the burdens of this life and go on to heaven -- which is our true home. The Apostle Paul declared, "I desire to depart and be with Christ, which is better by far" (Philippians 1:23).
But have you ever asked yourself why God hasn't answered your prayer (at least in the way you wish He would)? The reason may be that He still has a purpose for you down here -- something He wants to accomplish through your life. I don't know what it is, but I urge you to pray about it and ask Him to show you what it is.
I think, for example, of a widow I know who grieved deeply over the death of her husband. But one day she met another widow who also was grieving -- and she realized that God could use her to encourage and help this woman. And God continues to use her to bring comfort and hope to others who are grieving -- and through this, her own grief has lessened. The Bible tells us to "encourage each other" (1 Thessalonians 4:18).
Thank God every day for the memories you have of your husband. Thank Him, too, for the hope we have of heaven because of Jesus Christ and His death for us. But pray, too, that God will use you to point others to Christ, who alone brings light to our darkness.