Write a letter to yourself telling you what you need to improve in the coming 6 months.
You just got a rejection. And it wasn’t even a personal rejection, just an impersonal form.
Stephen King collected his rejections on a nail.
This rejection is not a condemnation of your abilities. Even if you did really think that one would be accepted.
You’ve started a good habit: Turn that story around as soon as you get that rejection – send it right back out to another market. Just don’t let a rejection get you down. Better writers than you have received many times more rejections. Just keep working.
Realize you cannot make everyone happy with your writing. The day will never come that every reader says, “This is fantastic!” Don’t keep trying to get there. It won’t happen. Make sure you’re writing for the reader who will want to read your work and don’t worry so much about the rest.
Find a way to be less dependent on others. For you to maintain a good consistent habit of writing, you’ve got to find a way to keep going, even when you want to talk about it with someone. You can always rewrite.
Find a way to write past that bad day. Use it! If you’ve got an outline, look at writing that scene where the MC is having a bad day – if you’re doing your job, she is having bad days.
And never forget the reason you’ve been writing for so many years – you enjoy telling yourself stories. As long as you keep on enjoying that, the rest will work out.