wow, it does sound like you are having a bad day
i can't imagine a court anywhere that would have you forced to make arrangments with your ex's new partner. in my experience that does not go over well with judges and shows an unwillingness to co-parent fairly. i would start proceedings, even if you wont be moving for a number of months, court takes a while to get things moving... well at least here it is that way. i cant see them not addressing the birthday situation very quickly, as he had them last year and is obviously not willing to be fair with you. i am wondering how long his new partner has been in the picture. it seems as tho they are trying to form a new little family with no room or consideration for you in their little unit.
i wouldnt wait, having roommates doesnt make you less of a parent, or your home less safe or appropriate for your children to visit and spend time at. i cant see him getting any better with how you described his response to you today.
i have a bit of a temper, i would get in my car and head on over and force him to let me see my children on thier birthday if it took waiting outside their door all day long and make sure that my children knew i was there waiting. otherwise who knows what he might tell them, that you had no interest in seeing your dd on her special day... or you couldnt be bothered to make the long trip... i would rather have my kids see their father for what he is, than have them think less of me as their mom. i have taken the high road for 12+ years and all it has got me is my children horribly p.a.s.'d and seemingly ruined emotionally by the actions and words of their father. from now on i plan on being more honest about who he is and what his intentions are and have been. i have found that being nice to and about my ex for the benefit of my children has only harmed them and empowered my ex to be a worse beast than he was when we were together. i regret it with all my heart. i wouldnt call anyone who feels that they and their time with the children is more important than the abscent parent's a sweetheart in any respect... i doubt he is anything more than the man you divorced and is only sweet when he is getting his own way and not havign to deal with your children's need for you in their lives.
your ex may seem like a 'sweetheart' with your children, but in all honesty could you really say that someone who would deny a child the enjoyment of sharing their birthday with both parents who brought them into this world, truly cares about his children's feelings or needs. doesnt sound like a sweetheart of a daddy to me.
you have all my sympathy, especially in having to miss your dd's bday. i have been denied every holiday and so many bdays that they are uncountable... my heart is truly with you