man, dating is hard but he isn't a jerk. Has he said he wanted to be exclusive with you? Many people date at the same time and yes it looks like you were one of two options (that you know of).
If i were you I would have just been honest and said that you saw the text from the corner of your eye and want to know where you stand because you can better use your time with someone who is more interested if he isnt.
Anyways, it's done now and you have your answer. Remember, you could also be put in that situation where you're still trying to figure out who you would rather spend your time with. It doesn't mean that they are bad people, it just means that the connection isnt strong enough, you'll find a better one :.