That small voice in your head telling you those things over, and over is the great deceiver. It is he who wants you to believe those things.
That voice that tells us we're not good enough, we don't deserve God's love or his forgiveness, and no matter how hard we try we fall short isn't from the Lord. I know, I've been right where you are and it's a struggle to get past it.
What you must do, is learn to forgive YOURSELF. The Lord already has.
None of us are perfect, we'll never be "good enough" and we all fall short of the Grace and Glory of the Lord. That's ok, He knows that. That's why Jesus came to be the perfect sacrifice the Lord required as forgiveness of our Sins. Your father in Heaven loves you so much, he gave His one and only Son, Jesus who forgave you your sins long before you were born.
There is nothing you can do to earn that forgiveness my friend, it is a gift from our Father in Heaven. All you have to do is accept it, embrace it and be thankful in heart and spirit.
That doesn't mean you won't slip and fall again, it doesn't mean you won't sin. You will, so will I and everyone else on this thread. What you must remember is that the Lord forgave you before you were born. His love was poured into you as he knit you together in your mothers womb, and his love has always been there.
Grab onto it, hold it like you'll never let it go, and forgive yourself. You'll never reach your full potential, or be what God wants you to be while you hang onto the guilt of sins past, and listen to the Deceiver's voice.
You are so much better than the voice that deceives you into thinking otherwise. Stop listening to it, calm yourself, and listen for the Lord.
Amen to that! That’s why Satan’s called The Accuser of the brethren.
One verse (of many) to keep in mind:
Hebrews 12:1-3 (NIV)
12 Therefore, since we are surrounded by such a great cloud of witnesses, let us throw off everything that hinders and the sin that so easily entangles. And let us run with perseverance the race marked out for us, 2 fixing our eyes on Jesus, the pioneer and perfecter of faith. For the joy set before him he endured the cross, scorning its shame, and sat down at the right hand of the throne of God. 3 Consider him who endured such opposition from sinners, so that you will not grow weary and lose heart.