Relationship drama. Need advice

Me and my man have been together for a year now. Last Saturday, we had our first threesome with his friend, my man, & me. Him and his friend have been super close friends since elementary. The reason we had the threesome was because he said he wanted to have a threesome with another girl but I said no. I would only agree to have it with a guy because I don’t want no bitch touching my man. So then I THOUGHT he only did the threesome because he thought he can get something out of it like a threesome with a girl but he was wrong. And now, he texts me this. He had been acting a bit weird since last Saturday. Im honestly hurt because I always had a feeling that he might be bisexual but anytime I would bring up the topic he would brush it off or avoid it. Please help. Im not sure what I should tell him. He’s 32 years old and I’m 19