Pure free will is only possible in the Beatific Vision because, when the soul has the Beatific Vision, it cannot sin. In other words, the soul has fallen so greatly in love with God that it can no longer offend Him, it falls anew with ecstasy for God at every moment, for God is All-Beautiful. The Beatific Vision is the vision of God, it is seeing God face-to-face. The soul can see God now, in this world, in as far as His Glory is reflected in the beauty of nature and His Holiness is reflected in the state of the soul, but in Heaven the soul sees God face-to-face. To help give you some understanding of the Beautific Vision, it is like a man who sees a woman of such beauty that she has captured his heart and he desires to love her - yet this is only a pale shadow compared to the Beauty of God. And since God is spiritual, His Beauty is beyond the imagination. We are used to physical beauty, but beauty is not only physical; there is also spiritual beauty, such as the beauty of love. So it can be found that God is All-Beautiful, Beauty Itself, and in Heaven, we will see Him face-to-face. (Sorry about so much redundancy!)
Adam and Eve, and the angels, did not have the Beautifc Vision because they first had to pass a trial. The angels were in Heaven, and Adam and Eve were in a paradise-garden. Both groups of creatures were tested, the former before the latter (because God created Heaven before Earth). The angels were given a test of obedience; if they passed, they’d get to see God; if not, they would lose Heaven. The angels had supernatural knowledge of God; they knew who He was, how important He was to them, and why He had created them. What test they had, I don’t know, but some of the angels failed the test and were thrown out of Heaven. Most of the angels, though, passed the test and they were allowed to see God. Adam and Eve were also a given a test of obedience; if they passed, they’d get the Beatific Vision; if not, they would lose immortality (in other words, they would die). Adam and Eve failed the test, and they lost the gift of immortality and were kicked out of the garden. Yet not all was lost; God promised to redeem them, which He did, by the death of Jesus Christ. The fallen angels, however, could not be redeemed, because their choices were irrevocable, given their great knowledge of God.
Free-will is the freedom to will good; free-will is a grace, a free and undeserving gift from God given to man for his greater good. God gave man free-will so he would choose God, so he would love God, because man was created in the Image and Likeness of God. But free-will can be abused, just like any grace can be; man can use his free-will to do evil. However, by uniting himself to God, man can become freer, that is, he begins to sin less; God gives him graces and his soul becomes pure, holy, and the holier a man is, the less he is able to sin, for the more he loves God, the less he is willing to offend God by doing evil. God desires to give men every grace, but we do not always want His gifts, so we do not always accept them, we throw away the gifts which we have received from Him. Hence, it is the more a man trusts in God, the more he prays to God, that the more graces a man receives from God. Mary, who was full of grace, is an example of this; she was so filled with God’s graces that she is the most holy creature in existence. She is so holy because she trusted completely in God, she gave herself entirely to God. Because God saw her absolute self-surrender to Himself, He gave her a singular grace which preserved her from Original Sin and from personal sin, so that she was completely sinless - absolutely holy - her whole life, conception to death. Because Mary was all-holy, a blazing mirror of God’s Holiness, some theologians speculate that she enjoyed the Beatific Vision. But no one knows for sure.
