Your fear is far worse than reality. Learn that and the emotion loses its power and you grow stronger. You can even use jealousy, insecurity, etc. to teach you about yourself. They are valuable. Pay attention to them and learn from them.
Respect is a form of love.
Respect yourself, set limits and boundaries and respect those of other people. Never tolerate abuse. You deserve better. Remember to be polite to your partners, they deserve it even more than the stranger down the street. Try not to save all your best stuff for one partner and take your partners for granted, especially when they are together.