Potentially NTA but there’s at least two ways to look at this.
Over the last five years has there been any negativity between you and her? If you think she wouldn’t want you there then don’t go.
However it it’s just a case of a friendship that wasn’t particularly a close one I don’t see anything wrong with going and paying your respects. I always think funerals are for the family rather than the deceased and families find comfort in knowing/thinking their loved one had a lot of friends who thought fondly of them. You don’t have to go and pretend to be upset or feel any sort of way but your presence there may bring ease to those who are grieving.