Just ask him those very questions. Simple and plain. I know a bit of his perspective as far as not wanting to hurt your husband. That in it's self is a very good sign. I am a firm believer that a secondary has to care for both partners and hold the primaries above everything else.
He's got a lot going through his head..maybe even trying to decide if he is poly capable as well.
Just ask him, vagueness is tiring and a waste of energy IMHO