I 100% agree with what elle said in earlier post, you have done SO much to keep contact with him and his mother (who, correct me if Im wrong, she didn't know you were pregnant with his child) he sounds like such an ar$e and he has messed you around non stop and will no doubt do the same to Amelia, she deserves so much more than that. You both do.
I would be fuming if I had got that response from his mum! Basically I read it as he is trying to do something with his life and dont bring him down.. so what he got a job (woopie).
Good luck to his new girlfriend with his up and down behaviour she will need it!!
I think its a good idea to keep the mothers contact details just in case Amelia asks questions as she has every right to know about her dad but I hope its not until she is a teenager and then will truely see what kind of person he is. Who knows she might not have any interest to actually meet him since she has such a loving mum with a great boyfriend
My partner has the opposite problem, his ex always used his son against him (you don't do as I say, you can't see your son games) and its not fair on the kid if the parent is the one to say they can or can't see their parent. He would be more involved but was never given the chance, always cut off unless he was running around after her.