A jealous heart can cause you a lot of grief. If you can't trust them, then perhaps it is time to move on.
Happiness isn't about working yourself into an early grave so that you can buy things that you don't need in order to impress people that you don't know or like. Don't get caught up going round and round in a cycle of endless consumption. It won't bring you the happiness that you seek. It's just a distraction.
It's often said that you have to be ruthless to get ahead; that's true in films and books, but not necessarily in real life. Being nice and ethical can be very rewarding.