I'm young, 26, but I've already had too much experience with abusive relationships and I think that you shouldn't have to be around the man that abused you, no matter what the occasion is. You can always do your own birthday party for your granddaughter at your place or at a restaurant that's is geared towards children (aka chucky cheese, Peter Piper pizza, ect). I'm sure your granddaughter will love having two get togethers and then you don't have to bother with your ex!

Does your family know about the abuse? Would they understand if you were straight forward with them and told them exactly what you just told us?