Yes, masterbation is a grave sin. Sperm spilling or not, it is still masterbation. Lustful thought are irrelevant. The fact that you are masterbating, is a selfish act. It is all about you, you, you. God specifically made sexual acts to be unified between a man and woman under a covenant with God.(AKA marriage). Masturbation is completely twisted. I have been caught up on this and have been progressing. I am on my longest streak of not masturbating right now for about 2 months straight. I pray that you find God’s love because whether you find it or not, He still loves you. God Bless You.