Frenchie your partner is who he is, and given the way you describe him, I would have thought his reaction is one that could have been expected. he is clearly a very self-contained person, who only has a limited iterest in personal relationships. if you have been together 8 years, you must understand this by now.
Suddenly your life has changed. It is up to you now whether you end your relationship or accept his attitude and on your side make it clear that your child and grandchild matter immensely to you and you will always be therefore them and will want to be around for them, you accept he has no interest in them.
Decide how much time you want to devote to them, perhaps, on average, say, one or two days a week, it could be regular child care (at the child's house), or holidays, or weekends away, and you will be doing that but you will not involve him.
All partnerships at some time hit crises and in good relationships you work them outtogether with respect for each partnes wishes.