I have been through the exact same thing myself and I can share what helped me.
I dont always agree with people who say ‘social media is not real life’. Most of social media IS real life. Those pictures are not photoshopped! Even if someone is going for a vacation abroad at the cost of something, they still ARE going to a vacation abroad. Not everyone who goes to great vacations with their spouse is getting divorced. So rather that telling your self not to believe in those pictures, accept the fact that some people have more than what you have.
Now what to do when someone in your circle is flaunting her life. 2 simple steps- first start maintaining distance from her (be it unfollowing on social media or watever) and second MAKE NEW/OTHER FRIENDS. Can’t tell you how important the second one is. Where your daughter is concerned I’d ask you to encourage her to do the same. The world is full of different kinds of people and you won’t necessarily gel with all kinds. You have to keep meeting new people to figure out whose company you enjoy with. Have your own bucket list of things to achieve and keep following your passions, those goals should not anything to do with what X Y or Z is posting on social media. You are NOT a failure. You are a good person, you do your best, you’ll get through this.