Perhaps a few things.
1. Pray before you "do" anything. Keep the issue in prayer, not asking for a specific sort of resolution, just that Lord have mercy, and His well be done. Pray also for your parents.
2. if you have not already done so, call or write an Orthodox priest, explain your situation and ask his counsel.
3. If you feel the tension racketing up, why not say a prayer, then talk to Dad and ask his counsel. Let him know your concerns, and where your heart is headed.
4. Find a saint…one whom your heart is attracted to, and if possible obtain his icon, and ask for his intercessions.
5. If a moment of confrontation with Mom arises, cross yourself, pray inwardly, and answer any questions calmly and respectfully. If the point is pressed, reassure her of your love, but let her know it is your intent at some point, God helping you, to inquire into Orthodoxy…whether sooner or later, that is what you will do, and there is nothing, so far as you know, that will change this, and if you continue to feel then as you do now, it is your intent to ultimately become an Orthodox Christian.
6. Bear whatever comes with humility, good or bad.
7. Any advice you get from anyone, especially from the internet, is best if double-checked with an Orthodox priest.