I am probably unique in that I have ever had to deal with jealousy. I have been practicing REBT/Cognitive therapy techniques for so long that I've changed how I view things like this in my life. I'd say this - You feel the way you think. If those thoughts are negative (What if he leaves me? Is he better than I am? Will he love him more than me?) then you are obviously going to have an acute emotional reaction to those things.
Try and remember why you and your hubby are together and change these negative thoughts into positive reinforcing ones (Isn't it great how this as invigorated our sex life? Wow I can obviously love two people so must my husband and boyfriend! My Husband sure loves me to be able to share our marriage with another person so intimately).
Hope that gave insight.