Afraid of becoming asexual. Please help.

Respected sir/ mam I am staying single and without sex for more than 4 years. Last time I had sex was May 2015. After that break up I went into depression and ate lot so gained 15 kgs. Right now I am obesed. I have extreme sex thoughts all the time. Initially I thought of getting involved in physical relationship without love but couldn't do that as I realised it was not me. I have become very very negative minded. Some of my well known people warned me if I am abstaining from sex for a long time I can become asexual.  Recently I lost my job for an ungrateful boss. I have become very lazy after this. Now every time I am thinking life is worthless. Whatever I do actually turns into ash. All the time I think life I will never get love, never get sex and a good job to survive well. I have lost confidence after leaving my job. I waste my time by stalking some over achievers on social media, I sleep a lot. I want to do a fresh start but for this kind of thought I can't restart. Please help.