If you are in a same-sex relationship, and you find out that your partner is not gay or bisexual, it's not necessarily a reason to end the relationship. If you both feel comfortable with the situation, it may be better to take your time before telling everyone else. Start by telling someone who you trust and feel reasonably confident will be accepting, and ask them to be there with you when you come out to others.
Many people who aren't gay or bisexual still worry that they are, and this can cause them to censor their behaviour or try to prove to themselves (and sometimes others) that they're not. For example, avoiding touching other people's bodies, or rehearsing arguments in their head about how men and women should behave. Compulsively checking their appearance to see if they look like they're gay or straight, or reading articles about how you can tell if you're gay.
Having feelings that suggest you are attracted to the opposite sex doesn't make you gay, and many people go through phases of sexual experimentation before they settle on their orientation. Having a crush on the opposite gender in childhood or youth doesn't mean you are gay, either.
It's not your fault if you have anxiety about coming out – homophobia and other forms of prejudice are alive and well in our society, and queer people are often discriminated against at work, in their communities and even within their families. Having to keep your orientation a secret can be stressful and overwhelming, but you don't owe anyone a disclosure of that kind of information.