Her fiance text me saying that I am a rubbish maid of honour and friend…

Hi, just looking for a bit of advice… Basically don’t know if I’m overreacting or not, but here it goes… My friend got engaged last year and asked me to be maid of honour, which of course I accepted with no hesitation. I planned the hen, helped her with invitations and even papered her living room wall for her but over the last few weeks due to family issues I haven’t been to visit her as much. I also had a text from her fiancé last week to say work friends have organised a surprise hen for this weekend and want me to go. I have explained that me and my partner are planning on taking his daughter to a local theme park as we were unable to do anything for her party that Sat and it was unlikely I would be able to go. He replied saying it was the Fri, to which I said that’s not a problem.
Turns out he got the date wrong, the hen is actually on the Sat. I have said I’m not 100% sure I can make it and as a result I have had her fiancé text me saying that I am a rubbish maid of honour and friend and that I’m just making a crap excuse not to go and I’m just obviously too busy to go. Told him that it’s been planned for weeks, which it has, and I’ve just been called a liar and told to remember it’s her special day… What would you do? Xx