Advice to increase confidence

So I went out with a female friend of mine and whilst we were hanging out, she called another friend of hers who I didn't know. I usually get awkward and silent in front of straight guys and that's what happened. I was quite all the time and my heartbeat fastened. It felt like puking. I'm pretty sure he thought I'm boring and not worthy of communication. I left after some time. Any advice or suggestions to overcome this feeling?