The thing that worries me is whether your husband knew about you being Poly before you married him? If you only told him after you married well that could really constitute a bait and switch. Now I know he said he accepted it, but it was admittedly a lie based on fear. Since you made the commitment to him and you have no other commitment at the moment, you have to make a choice between putting all halt on outside romantic attachments and see whether you could ever make your husband feel secure enough to accept Poly, you can accept your husband wants a mono marriage and live with that or you can end your marriage.
Whatever happens you can't have Liam right now and pursuing it would be quite selfish at this time.