I would give a therapist (and you) the final word on this. My inclination is that you should try to go to the funeral even if you just drive up and sit in your car crying. I hope that there are supportive people willing to go with you if that would be helpful. If you would find it helpful to have supportive people and you don't know of any, maybe a grieving support group would be the place to find companions for the funeral.

If you cannot go, and anyone tries to judge you and you find out, tell them that you did everything possible to go and had a breakdown or whatever. Funerals are normal places to cry. People will relate to some extent and feel sympathy/empathy.