I'm nearly thirty years older than you. Many times life has seemed meaningless and I have gone to bed thinking that the future is pointless.
When things are bad and you feel down, it is so hard to see past everything, but trust me, things do get better. I won't lie, things get better and then something else will no doubt bring you down, but that's life, the good and the bad,the rough and the smooth.
Whatever situation you are in, I promise you, it won't be like that forever. Something is always just around the corner.
You are twenty one. I am a completely different person with completely different tastes, likes and dislikes now.
Things do change, you will change. Life can be crap, but it can also be filled with joy and fulfilment. You are just setting out, you have a long journey ahead, don't look back but keep on going and explore and enjoy every twist and turn your journey in life takes you.
Jealousy usually stems from feeling insecure. Try a few self help books.
This one looks good
www.amazon.co.uk/Raise-Your-Self-Esteem/dp/B002SQCZFM/ref=tmm_aud_title_0
When you feel this low at night, please go to bed thinking that the horrible day you just had is over and tomorrow brings you different things.
Xxx