Test: We have all experienced what you have inquired about. This is what I've learned about this with our thoughts. Our minds are the battle ground for the Christian. This where the devil really has a hay day trying to tempt us to sin or condemn us. First of all before I share there is a promise you need to get a hold of.
Romans 8:1 There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.
Walking not after the FLESH IS THE KEY. Then the devil will have little to accuse us for. This verse is what you stand on when you are accused.
I John 1:9 IF we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
You notice the condition in the word IF WE CONFESS OUR SINS. We have to do that first. REPENT!!
Here's another weapon of our warfare. James 4:7 SUBMIT YOURSELVES THEREFORE TO GOD, Resist the devil, and he will flee from you.
Submitting to God first, then you deal with the devil. We have been given AUTHORITY FROM GOD TO RESIST THE DEVIL. This is your sword of the Word of God to resist the devil.
Years ago, I had a terrible battle at the hospital where I worked and was under severe attack by the devil. Our attacks can come because of our flesh, the world or the devil. Well, I had all three at once, but the Lord doesn't allow more than you can stand without giving you a way of escape. It was a training time in the Lord as a young Christian. The Holy Ghost gave me some verses to copy, memorize, & carry around in case I was attacked big time. I can't begin to tell how bad it was, but the Lord saw me through. Glory to God!!
These are the famous verses: 2 Corinthians 10:4-6 (I only memorized v.5) v.4 (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds.)
v.5 Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;
v.6 And having in a readiness to revenge all disobedience, when your obedience is fulfilled.
Last comment on your question about heaven. In heaven we will be as he is, and we will not have this sinful flesh any longer to contend with. There is no sin in heaven, so obey the Word of God now and you will be there. Just stay on the narrow way that leads to life. Matthew 7:14
This will tell you why you don't have to be concerned if you will sin in heaven or not. It's in I John 3:2 Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, WE SHALL BE LIKE HIM; for we shall see him as he is. Praise God, HALLELUJAH!!
High Desert ITD: Agree with you on OSAS. Amen, Amen
PROCLAIMING THE TRUTH (see profile) John 17:17 Sanctify (set apart) them through thy truth: thy word is truth.