Short answer to the question of the thread: NO. Absolutely not.
There is a lot of discussion and processing that needs to be had before either of you begin engaging other people, as well as individual work on trust in the relationship and time for that to happen.
Have you told him about the kiss?
And please, don't think agreeing to poly at this point will solve anything. You'll be left even more shaky and with you already feeling powerless it can only go downhill from here, without any prior work.