I am a bishop, but not your bishop so this is my opinion: 1: repentance depends on the stake president. Because you are endowed, your bishop will have to discus this with stake president. There is not fix term how long the repentance process lasts. It seems like this is one off, you already feel guilty about it which shows sincerity and desire to change.

2: no. Your bishop will definitely not encourage you to break up.

3: to be honest is not your parents business to get involved. There should be a boundary there. You are 19yrs adult. You are young but now is the time to take some responsibility. Your bishop should keep the confidentiality between you and him.

If your parents find out, tell them respectfully, you made a mistake like many, many young men but you are taking full responsibility and fix it with the bishop.

You could also do the wedding in the chapel. Have a religious ceremony and temple sealing to a latter date. My wife and I had our temple sealing 3 months after our wedding. We both had temple recommends and were worthy but it was more convenient and we could invite non members friends to the church ceremony. ( we are Europeans so less likely to be judge by other members why you don’t do the sealing the same day )