Am I being ignorant or what?

i wouldn't want to go either. if these are all lies, he is not a nice man and doesn't deserve your respect of a visit. instead he should be extending an apology to you. your partner should be standing up for you, instead of expecting you to go to his dad's birthday. you are not wrong. good luck in whatever you decide to do, but, remember to always have respect for yourself, even when others don't. that's the only way you'll know what to do in any given situation. stand up for YOU.