legally, there is nothing YOU can do just like you were advised. stop listening in on calls. look, i'm also married. i deal with my children's father as well. the only time i need my husband to listen in on a phone call is when the NCP gets irate and his statement may be needed as a witness. my husband is not concerned with me getting back with the NCP (ew). so neither should you be. if you loved your husband, stay out of it. let the child love you as an additional role model and not a replacement. all you are doing is causing the child undue stress later on in life. that child should not have to feel the strain of feeling more devoted to anyone parent over the other. as far as being there for pick up or drop off, the mother is being kind of stupid about that. can he drop you off at a corner coffee house for the exchange and pick you back up. the whole time should take no more then 5 minutes anyway.
and no, being fiancee'd or married does not give you any additional rights. i learned that one already. it sucks, but hey....my kids look at my husband as part of their family. and that's all that really matters.