I hate opening up because it only makes things worse

I'll go straight to the point. I never tell my feelings to people because whenever I did it, people went away.

This has happened like 5 times in my life (I'm 17) and I open up to them when I feel comfortable enough and really trust them, but it always ends the same way.

Recently I opened up to a friend which I used to have feelings for, she did for me too, for a period of time. I never told her about my situation because of fear she might go away. That was until yesterday and she doesn't even talk to me anymore. I don't get the point of people that say "Don't hold your feelings", if I never spoke out they would still be with me now. (In advance sorry for grammar mistakes, English is not my strong point)