What are your plans for tonight?
That's a tough place to be in; not necessarily going to get better/go away entirely any time soon. For me it's all about self care when that stuff comes up; doing something physical to help move those emotions through the body (jog, go to a yoga class, do a hardcore workout video, have a hot bath and a cool drink and do some serious deep breathing). It's about respecting the limitations within your body/mind by doing caring, self loving things while those emotions are happening - ie, the way that we rock babies when they cry to comfort them - rock & hold yourself, have a good cry, write down some points to take to a counsellor at a later date. Love & take care of yourself, and know that you're worth every second of self care that you can give yourself when you're feeling vulnerable and lost/jealous/fearful/angry/etc.
Instead of trying to work so hard on those emotions and eradicate them, my question is this.... what are your plans on their night together? Do you book fun friend nights, sleepovers at a friend's place or anything of the like? Is it time for you to negotiate another relationship for yourself so that you have your own nights with another partner too?
If you make it about what you're doing for yourself, and give that self care to yourself, you might jes' find that the fun that you have on their nights together starts making you look forward to your time with yourself/friends/family. reward yourself with love, care, time and attention for being such a giving, sharing, loving partner, and know that the way you feel is NATURAL.