What should one do to remove the disease of jealousy
We should understand that everything is from Allaah Jallajalaalahu and for a particular and valid reason. When we understand that and accept it, which is, of course, is part of our Imaan, then if we feeling jealous, it actually is objecting against Allaah Jallajalaalahu, which no Muslim will ever do. Meditate on this and it will help a lot to remove these feelings of jealousy.
Also remember when we feeling jealous about anyone, anything we are burning in our hearts, we are miserable, we feel down and bad, while the other person is enjoying his life, what sense does this make, that the one we are jealous on is enjoying while we are suffering. Meditate on this too, it will help tremendously to remove this jealousy.
Also meditate on the fact that it is a ghuna e kabieraa, a big sin, why suffer and yet incur a major sin. It just does not make sense in the least bit.
On whom you are jealous speak good about them in front of others, force yourself, praise them, invite them to tea or so, send some little gifts to them. By doing this, this jealousy will be removed right from the roots and replaced by love and kindness for them, which will make you also feel very nice and happy. Also make Duas that Allaah Jallajalaalahu opens your heart for them