Dont worry about ruinned friendships , if someone is your real friend accepts you ,the real you . and your sexuality. Dont worry about bullying or haters. I know there are gay or bisexual guys out there that are not too ornot at all flamboyant .If you are about to come ouut then make sure your parents are not homophobic and if they are there is a small chance that if they dont accept you right away before they accept you they may take you some privilages thinking that 'it is just a phase' e they could take you your pc or car or try to get in the way of you meeting with your friends .There are not a lot of chances of these happening cause a. you are 18 = an adult and they see you more mature now and independed , you are not 15 which would make the situation harder and because of b THEY LOVE YOU so sooner or later they will accept you. I suggest you first come out to your friends and parents and siblings , the people close to you, after them if everything goesright and you have someone to trust you can come out to the rest of the people when you are ready , and be then considered 'openly bisexual/gay' .I hope you the best