Your honest pouring out of anger and frustration has been heard, and it is good that you have brought this burden into the light before the Lord rather than letting it harden within you. The wound you describe is real. To be left without answer, to be abandoned after words of lifelong intention, and to be met with silence where there should have been honest speech, is a bitter betrayal. It is no small thing, and the Lord does not despise the cry of a wounded heart.
You have felt the sting of being betrayed by one who claimed the name of Christ, and that makes the sorrow cut deeper. Our Lord Himself knows this pain. He was betrayed with a kiss, by one near to Him, and Scripture was fulfilled in that treachery. In that betrayal sin reached its height, yet even there God was wiser than the adversary, and Christ became able to sympathize with us in every point. He knows what it is to be forsaken by man, and He is not distant from your grief.
You speak of an intense internal anger, of wearying yourself to read the minds of others, and of being left without answers for how to improve or move forward. That restless searching will only exhaust the soul. Man cannot see the heart as God does, and we are not called to live as mind readers. The Lord does not deal with you in that way. He speaks plainly in His Word, He invites, He promises, and He does not leave His people to guess at His will.
There is a word that meets your condition from the Psalms, There is forgiveness with Thee, that Thou mayest be feared. This is the great wonder, that forgiveness is with God, and that it is full, absolute and eternal through Jesus Christ His Son. If you tremble under sin and sorrow and desire forgiveness, hear this, there is forgiveness, not by measure, not up to a certain point, but a complete blotting out of the debt for every repenting and believing sinner who trusts in Christ alone. For salvation is through Jesus Christ alone, His blood and righteousness, and there is no other name by which we must be saved. The record of debt is nailed to His cross, and the gifts and calling of God are without repentance.
And with that forgiveness comes healing. The leaves of the tree of life are for the healing of the nations, and the least thing about Christ has healing virtue. The inhabitant shall not say, I am sick, for the people that dwell in Zion shall be forgiven their iniquity. Healing and pardon are placed in happy conjunction. When the heart is forgiven, the Lord begins to heal the wound that sin and the sin of others has made.
This does not mean the hurt will vanish in a moment, nor that you must pretend it was not cruel. What was done to you was unkind and wrong. To use another as a placeholder and then to depart without a word is not love, and it is not the way of Christ. Yet the call of God to His people is to forgive one another, even as God for Christ's sake hath forgiven us. It is a joint work of mutual forgiveness among Christians, and for those who have received so much manifest forgiveness, to forgive should become as natural as to open the hand. This is not to excuse the wrong, but to release your heart from the prison of bitterness into the freedom of Christ. Vengeance belongs to the Lord, and He will judge righteously. Your part is to place both the anger and the person who wounded you into His hands.
God's good design for love is not abandonment and silence, but a lifelong covenant of one man and one woman, where intimacy and life together belong within that sacred vow before Him. That design is for our good and for His glory. When that design is not honored, wounds follow. The Lord would have you walk now in purity, in truth, and in patience, not seeking to decipher the unspoken thoughts of others, but seeking first His kingdom and His righteousness, trusting Him to guide your steps and to shape your heart for whatever He has prepared.
We will pray for you.
Our Father, we lift this wounded one before Thee, who is wearied with anger and frustration and with unanswered questions. Thou knowest the betrayal she has suffered and the silence that has left her searching. Lord, grant her Thy forgiveness through the blood of Jesus Christ, and assure her heart that there is forgiveness with Thee, full and free, now and forever. Heal her as only Thou canst heal, let the healing leaves of Christ be laid upon her spirit, and turn her anger into prayer and her confusion into trust. Teach her to forgive even as she has been forgiven, not by her own strength but by Thy Spirit. Keep her from bitterness, guard her mind, and give her wisdom to walk in Thy ways, to seek counsel among Thy people, and to wait upon Thy good providence for the future. We pray also for the one who left, that if he has sinned against Thee and against her, Thou wouldst bring him to repentance and to true faith in Christ. Let Thy will be done in both lives, and let this dear soul find her answers not in the mind of man, but in the heart of her Savior. In the name of Jesus Christ our Lord, Amen.
Cast your burden upon the Lord, and He shall sustain you. Continue to bring this grief to Him in prayer, stay under the preaching of His Word, and seek the fellowship of faithful believers who can walk with you toward wholeness.