Thank you so much everyone for responding. It has made me feel so much better that it seems to be her problem not mine.
I have discussed this with a few mutual friends now and they are all of the opinion that friend and her hubby are acting very strangely and even though they are not as close to them as I was have really noticed the change and think it's very odd to disappear and not want to keep up friendships at a time most people want and need them. Also they feel like the fact they kept it secret for 5 months and haven't really seemed excited or wanting to speak about it gave the impression they didn't want people involved, so her accusations that no one offered to help them or is happy for them etc is like a request which is opposite to the message they have given.
I have decided not to contact her or her husband and to simply smile if I see them around church etc. They can come to me if and when they want to sort things out. My problem though is that we are in the same home group for church which meets once a week, always in someone's home. I don't want to leave the group because I really enjoy it and get on well with the other members, but there are only 9 of us so it is hard to avoid someone.
How should I be towards this couple when they are there? Granted this isn't often at the moment, but I don't want to appear cold, but nor do I want to be overly friendly towards them either because they have not been in anyway friends to me recently. We usually have a time of chatting and catching up, then bible study, then talking about anything we want prayer for and what is going on with us, so it's kind of important we can all communicate with and feel secure with each other...