Do I think you can have a healthy marriage even if you've not remained emotionally and physically pure? Of course! If I didn't, then I would not believe in a God of grace.
God can heal, restore, and cause there to be a newness to your heart even if you've given it away.
If you have already given yourself away and now God's convicted you of emotional purity what should you do? Most likely you've already done a 180, you've turned and are walking closely with God. If you've been convicted just remain in that conviction.
There was a gal I knew who gave herself away physically when she was in her early 20's. After God broke her and brought her close to His side, she repented of her sin and never went back. She was not physically active again until her wedding night! God healed her, restored her, and has used her testimony of His goodness and grace.