The devil sure likes to remind us of our wrongs. He likes to throw our past in our face and make us think "Someone like me isn't worthy of His forgiveness." He wants to keep you from accepting the free gift of salvation from the Father. The Bible says Satan is the "accuser of the brethren" who appears before God day and night with accusations against believers (see Rev. 12:10). The guilt your feeling is NOT from God! Satan just wants to drive you away from Him by using shame and depression as his tools, but you must fight back with God's Word and with your faith.
Pray, pray often, reflect on these beautiful words from His word:
1 John 2:12 I am writing to you, little children, because your sins are forgiven for his name’s sake.
Isaiah 33:24 And no inhabitant will say, “I am sick”; the people who dwell there will be forgiven their iniquity.
2 Corinthians 2:10-11 Anyone whom you forgive, I also forgive. What I have forgiven, if I have forgiven anything, has been for your sake in the presence of Christ, (11) so that we would not be outwitted by Satan; for we are not ignorant of his designs.
