The biggest thing holding me back from telling anyone that I am gay is the feeling that I will hate my life afterwards and that I will constantly be thinking about my sexuality and how people think of me because of it. I'm also nervous that I will constantly regret coming out in the first place because what's done is done and there would be no going back. At least by not coming out of the closet I still have the options to come or not come out of the closet. How do I become more secure that my future, after coming out, will be better than the one I am currently living (closeted)?
Bearing in mind that you don't have to come out at all, it really boils down to whether you would rather people knew or not. There are pros and cons to both sides. If the former, then it's a matter of deciding who to tell first - but I'm sure you'd have somebody in mind already - and then taking the plunge.
It's normal (that's right... normal) to experience feelings of doubt and nervousness and to question if it's the right thing to do. It's also normal to process various scenarios in your mind, and even though it sometimes it works for you, it can also work against you as you overthink and analyse what might go wrong. How do you become more secure? By listening to the testimony of people who have been through the anxiety and nerves and faced them down, freeing themselves of the huge weight that comes from that stifling closet. Is it a risk? Yes, it is, but it's a risk worth taking. To live authentically, is well worth it, I assure you. Even if some people do think badly of you, you will find yourself having better and deeper relationships with the people who love and accept you and that makes a huge difference.
