Idk anymore

It's my birthmonth and lately i haven't been that well- physically, emotional and mentally. Idk what's wrong with me but it's just that I guess i haven't vented out my feelings in a very long time so it kinda got a negative effect on me? It's been effecting my studies especially. I tend to avoid venting to my sister because she always ends up telling my parents about it and I don't vent to my friends because they use it against me or just plain old backstab me. And I've been trying to ignore it or just tell myself that "you can do it" or "it'll be better tomorrow" but every single day, I feel more and more down and I feel like I'm gonna burst out crying any minute. I just dont know what's wrong with me. I'm used to being the therapist friend, and being the older sibling to my sister (even tho I'm the youngest) and its like telling me that "you don't deserve to be sad because they clearly have it worse than you" or smth like that- but yk- I'm kinda jealous cuz when my friends or sister vent to me and they tell them that I should keep it a secret, I do. But when it's my turn, they always end up telling other ppl which is one of the reasons why I don't vent anymore. Idk man, I've been having thoughts of sui or just attempting all month. Idk