You can do the diagnostics online, using the PHQ9 or other depression assessment, but from your message with some judicious cutting and grouping:

"I have depression. .... I just feel sad now.... for no reason." Inexplicable sadness that does not resolve-check.

"It is pathetic....a whole bunch low self esteem and low confidence issues; Thoughts of how worthless i am" Feelings of worthlessness--check

"people scare me, I am starting to hate social gatherings and people" Self-isolation is a standard sign as is not finding pleasure in things you used to enjoy. check

"i am starting to realise that i am suffering from sexual addiction." Maybe. I don't know the criteria, it might be something else.

"i feel like a loser with no self control. An animal. A useless, worthless, neanderthal who cant control herself and be independent by herself." Feelings of worthlessness again. BTW, no one is worthless, no one is useless, and you are definitely not Homo neanderthalensis which are extinct. The current scientific designation for the modern human is Homo sapiens sapiens, therefore you are not a neanderthal. Note the two "Sapiens" which means we modern humans are double smart. Being double smart, though, means we can tie ourselves in knots double fast.

"i would like to disappear off the face of Earth. " Houston, we have a problem because you just indicated that you don't want to be here anymore, which makes you seeing a doctor really really important and urgent.

Maybe going to the ED is not a bad thing. I would print out your post and hand it to them, then you won't have to explain it all. It can be a bit embarrassing, but in times like these I think of this sign that was up in the VA when Dad had Cancer:

It takes the STRENGTH and COURAGE of a warrior to ask for help.