If Liam doesn't want a relationship with you, and you aren't sure if you want one with him, why did you kiss? Seems like playing with fire to me. It also seems like you are letting this crush go to your head and you are not thinking clearly.
You and your husband need to look at agreements you made and see what changes are needed now. Keep talking, talking, talking. Leave Liam alone for now. Don't make it even more messy by being around him, unless you really just like creating drama.