Jeez, families don't make it easy sometimes do they, but then I guess they have their own reasons. Moggy is right, it is selfish of them but not necessarily in a vindictive way. Some people don't realise how easy it is to keep in touch, some people think they are never going to see you again, some people just downright don't want you to go.
In my case, my father was fully supportive and actively encouraged me to go, saying I would never have this opportunity again. My mum, on the other hand, was not happy about me going and, whilst she tried to be supportive, I know she disagreed with my decision (especially given the fact that I was leaving 3 of my children behind). She's since been here for a holiday and now appreciates to some extent, just how much better our life is over here, but I don't think she'll ever 'forgive' me for leaving. I came out here with the attitude of 'I'll give it a try and if it works out, I'll stay' and it has worked out - much to the surprise (and possibly annoyance!) of people who thought I'd be heading back to the UK within a year or two. I must admit there was an element, in the beginning, of 'well, I'm here now and I'm going to stay whether I'm happy or not, just to prove people wrong' but now, this IS where I want to be. It's taken a lot of sacrifice and it broke my heart to leave my kids behind, but I would never be happy back in the UK on a permanent basis.
Moggy's given you some good advice Bermy Girl - arm yourself with information and be prepared to defend your decision to come to NZ - perhaps write a letter to them, explaining things to them. Tell them how they will be able to see and speak to your son (webcam, email, phone, MSN, etc). I am sure they already know what a good mum you are and that you believe you are doing the best for his future, they just need to know WHY moving to New Zealand is the best for him.
Good luck
