JOEL - If that member has progressed through all the required steps of repentance as directed by his Bishop, he can receive complete forgiveness and regain full standing in the Church and with God again.
As Isaiah said, "Though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool" (Isa. 1:18).
The repentance may require a period of disfellowshipment or excommunication depending on the circumstances. But by demonstrating an abhorrence for past sin and a commitment to righteousness, the repentant adulterer may, after an adequate period of probation, become fully reconciled to Christ, rebaptized if necessary, and reinstated in the Church and find forgiveness from God.
After the Bishop judges the person worthy, he can be married in the Temple and look forward to receiving exaltation in the highest degree of the Celestial Kingdom with his eternal companion, assuming of course that person does not do anything else wrong that would disqualify him. God of course is the final and ultimate judge in such matters.
The repentance process must be completed while you are still living in order to achieve exaltation. You won't have the chance to do it after you die.