Not knowing how much to share

I feel a lot and I feel very deeply. I think about things even more.
Sometimes I feel unbelievably low and sad and worried and generally unhappy and I am never sure how much to share- especially with the people that I am closest too.
For some reason it is so much simpler and easier to share emotions and thoughts and dilemmas with people that you do not know personally. It's easier because those people are distant. They may be impacted by your words or feel comforted that they are not alone in feeling a certain way, but their lives are not directly impacted by mine, and therefore I do not have to worry about my actions or feelings having a direct impact on their actions or feelings/ or affecting a relationship (because it's ultimately non-existent/ very distanced.)

People that I am closest too are, and relationships can be affected, and this is why it is tricky.

I have moments in which I feel incredibly awful- sometimes for a reason, sometimes not. Understandable. People deal with things differently.

I don't ever want to make the people around me, the people that I am close to and feel strongly about feel bad because of something that I am feeling. I do not want to make others feel sad, I do not want to make others feel worried or concerned about me, I do not want others to feel that they desperately must try to entertain me to make me feel better when I am not doing my best. The difficulty is, that I do want those people to understand. If I do not explain my worries or my sadness or my concerns then I feel distant, and not really myself. I feel that if I don't explain things or show how I am really feeling, then I'm not being truthful to the people that I care about most.

 I want to be positive around people and I want to answer "Oh yeah, I'm doing great, I'm having a really lovely day and I have lots of positive things to look forward to" when people ask me how I am, or what my plans are and I KNOW that there are lots of positive things to look at and lots of happy things to focus on and that at some point I most definitely will feel really great and will have a really lovely day- but the thing is, sometimes it feels completely impossible to focus on those things.

Somebody particularly close to me often says that it's just a mindset, and I totally agree. The trouble is, when your mindset is automatically negative, it's not as easy as merely telling yourself to smile and think about happy things and go and do something fun and then it'll all be ok. These things help, sure- but they don't necessarily solve when you're stuck in a sad cycle. People that don't struggle with intense sadness perhaps will not be able to understand what it's like to get to 3 o clock and feel uncomfortable and sad (If this is the case, that's amazing and I, along with many people are extremely jealous.)

So this is my dilemma. I do not want to have a negative impact on anybody else's life, nor do I want to be viewed as a pessimistic or overly negative person, however I know that sadness is often a big part of me, and that I don't always know how to deal with it and that I want people to understand me for me.

When I'm feeling low and people close to me ask me how I'm doing, I don't know whether to answer positively just try to cope with the real feelings without impacting others lives and without making people think that I'm being dramatic and overly pessimistic. Or whether to answer truthfully if I am feeling low, and let people know that sometimes I'm actually not doing too well.

What are your thoughts?

All my love xxx