2. Pastor, is it okay for me to maintain a friendship with another male that I once had a sexual relationship with and my husband doesn't know anything about it? He is a good friend and I want to stay close to him as a friend only.

It is not okay for you to maintain a friendship with any past lover.  You will always find some imperfection in your present mate just by comparison.  Our imagination will always find perfect in our past involvements while we face imperfections in our present reality.  When the people came out of Egypt they always wanted to go back as they faced hard reality of there present wilderness journey.  All they chose to remember was the meats and watermelon.  And what they chose to forget was all the beatings of their hard taskmaster.  You will never put the energy into your present relationship when you are always looking back.  This person is deep into your life and the further you get away from them, the more freedom you will have to love the imperfect gift God has given to you in your husband.  1 Corinthians 6:15-20  ¹⁵ Do you not know that your bodies are members of Christ? Shall I then take away the members of Christ and make them members of a harlot? May it never be!  ¹⁶ Or do you not know that the one who joins himself to a harlot is one body with her? For He says, "The two will become one flesh."  ¹⁷ But the one who joins himself to the Lord is one spirit with Him.  ¹⁸ Flee immorality. Every other sin that a man commits is outside the body, but the immoral man sins against his own body.  ¹⁹ Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own?  ²⁰ For you have been bought with a price: therefore glorify God in your body.

You may be still having an affair with this person in your mind and not know it.  The bible says we must flee immorality.   Matthew 5:27-28  ²⁷ ¶ "You have heard that it was said, 'You shall not commit adultery';  ²⁸ but I say to you, that everyone who looks on a woman (or Man) to lust for her has committed adultery with her already in his heart. 

If this is the case, ask God to forgive you 1 John 1:9 and He will because that sin has already been paid for by the death of Jesus Christ.  Go and sin no more.  God wants you to be madly in love with your mate as He is in love with the other members of the Trinity.  God wants you to spiritually grow and be just like him.  Matthew 5:48  ⁴⁸ "Therefore you are to be perfect, as your heavenly Father is perfect.  1 Peter 1:14-16  ¹⁴ As obedient children, do not be conformed to the former lusts which were yours in your ignorance,  ¹⁵ but like the Holy One who called you, be holy yourselves also in all your behavior;  ¹⁶ because it is written, "You shall be holy, for I am holy."