"I don't deserve to be forgiven for this particular thing"
How it sounds in your head: I get grace for 'normal' sins, but this one is different. This one was too calculated, too hurtful, too shameful. There are levels to sin and mine crossed a line that grace doesn't cover.
"But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin."
-- 1 John 1:7Source: Religion ranking sins—creating a hierarchy where some are 'forgivable' and others require extra penance, nullifying the sufficiency of Christ's blood.
The specific nature of what you did feels uniquely disqualifying—you can extend grace to others for 'lesser' things but yours carries weight that feels heavier than the cross. Society's judgment of this particular sin reinforces that it's 'worse' than others.
Manasseh sacrificed his own children to demons, filled Jerusalem with innocent blood, practiced witchcraft, and led an entire nation into abomination. When he cried out to God from captivity, God IMMEDIATELY heard him, brought him back to Jerusalem, and restored him—no probation, no 'working off' his child sacrifice.
I REFUSE the lie that my sin is categorically different from sins the cross covers. IT IS WRITTEN that the blood of Jesus cleanses from ALL sin—no exceptions, no hierarchy, no 'too far.' I do not have authority to deem myself unforgivable when God has declared me forgiven. My feelings about the severity of my sin do not outweigh the SUFFICIENCY of His sacrifice. IT IS WRITTEN that if the Son sets me free, I am free INDEED—not 'free except for that one thing.' I stand on the FINISHED work, not on my assessment of whether I deserve it. The BARAK blessing covers those who LIED and DECEIVED and MURDERED—and they were still protected, still blessed. How much more does the BETTER covenant cover me?
The Father doesn't have a 'too far' category—the blood covers what religion says is unforgivable. He's not calculating levels of sin; He's celebrating that His Son's sacrifice was ENOUGH for the worst thing you could ever do, and He's already moved you from guilty to RIGHTEOUS.