I told my dad I thought I was bi. He laughed. Taken aback, I asked him what he thought I was. He laughed and said, "I honestly don't know." He might think I'm a confused tumblrite. I'm very afraid of turning out straight now... He'll laugh at me.
Laughter does not always imply that the person thinks what is happening or what has been said is actually funny. People will often laugh when they are happy, sad, uncomfortable, losing their mind, etc. His responses may have indicated that he wasn't necessarily comfortable with the subject matter and laughter is not an atypical response in those situations. As insensitive as his reaction may have seemed, I would encourage you to not let it get you down. Let him laugh while you go on about your life, figuring out what makes you happy.
As Tigre said, laughing could be a sign of uncomfortability. I've read that men tend to joke and play around because we're typically less comfortable with intimacy, and that's a way to deflect that uncomfortability. Give him some time to digest what you've just told him. You've taken years to try and figure this out about yourself, he needs time to get used to it and adjust to some big news you've just told him.
