Recently I've found myself in a terrible situation because I feel myself getting jealous of a friend of mine. And I feel terrible because I can feel it ruining our relationship. And I'm trying to not have these feelings towards her but I fail a lot of times. What can one do to avoid feeling like that. Any supplications one can do to ease this feeling?

Its good that you have come to realize this at least. Its one instinct that comes to all, and if it is progressed, it will go leaps and bounds and destroy ones faith
Therefore, this undesirable instinct must be curbed with all the force at the disposal of a person. It should not be allowed to flourish and grow. If the instinct of envy is allowed to persist, It will reach such proportions that fighting it out will not be possible.
The first thing you have to do is to inculcate in yourself that whatever your friend has, the giver of the blessings in only Allah and none else, least of it herself. Pray to Allah to bless you with better than that and be happy that Allah can bless a person to such an extent.
Don't ever wish that the blessings being taken away from her because that would mean you are taking in to the instinct of jealousy and making it grow. Don't let shaitan get the upper hand with this undesirable character trait.
Praise her in front of people so that you can share the happiness of her blessings. This is so remarkable an action that you will really begin to feel the happiness even if you did it half-hearted or pretentiously at first. The great thing that will come out of this is that Allah will grant you the same blessing and better than what your friend has inshAllah.