This idea that you need to "get over it" is insulting to you and your feelings. They hurt you by lying to you, and they need to go a long way towards helping you mend it.
If they care so little about you that they are not willing to do this, then I think that you need to question whether this is really a good relationship for you.
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb