Yes of course it can be done but your problem is that you are expecting that it be done straight away and will all be plain sailing from there on in. IT IS A PROCESS!!
You did a good thing by sharing your feelings with your husband and then somehow had them invalidated by "ignoring" the conversation. I am confused by that one. Communication is vital, you can't afford to ignore conversations and either can he.
Examine your fears and insecurities (the monster that rises). Do you fear him ending up loving her more than you and leaving, or are you envious of their intimacy and connectedness? If it is the latter then, as I've said before you both need to work on regaining that. Listen to what the monster is saying, monsters should not be ignored either.