I am not a therapist, but everyone goes through sad times, and quarantine isolation is getting to everyone.  This is just some advice that I hope helps.  Remember, it's ok to ask for help (going to a therapist isn't the end of the world or a shameful thing to do); and also that yes, you do matter.  People care about you.  I care about you (even if we've never met, because I'm sure you are an amazing person).  Hang in there, it will get better.