I have anxiety, how can i control my feeling when am about to go out?

Anxiety: If you know you are not going to do well no matter what, just avoid going wherever you develop anxiety. Taking a medication before exposure, doing breathing exercises (google them), taking someone with you to help cope or distract you may work. I say a prayer when i know I am going to be in a stressful environment and it works for me.

Anxiety: Doing some breathing exercises first can help. You don't say whether you're already getting treatment for your anxiety, but it would be a good idea to see a psychologist or other therapist for this. There are very effective therapies that go beyond deep breathing, etc. You could have agoraphobia, a form of anxiety disorder. If you do need medication, a psychiatrist can fully evaluate & help you.