If from childhood u feel trapped in a wrong body, u shouldnt think of getting into relationships, until u decide on which way u want to live. then only your parents r involved and they should be able to understand, if they really care for u. Even if they dont, if u decide to go on transistioning, it is perfectly OK and u cannot be called selfish.
Regarding a married married person. just dressing will not be a problem, if ur SO accepts it. If it goes further and leads to transitioning, then one should think of the family first. marriage and starting a family is your decision and u have made that commitment on your own as a man, without anybody forcing u to do that. In that case you it is your responsibility to honour your commitment as an husband, as a father and you dont have a right to say, i dont care and go into transitioning. that will be pure selfishness and insensitive
there is an interesting page on bill of rights, for cds and cds's wives
http://www.tri-ess.org/Wives_CDs_BofR.html