It's just another night, you're not the first or last to feel this way.
This is perhaps straying too far into Interpersonal.SE territory, but as someone who suffers anxiety and similarly had panic attacks at their first work Christmas Party (and team day out, and company bus trip to the cinema, and team lunch, and performance review meeting...) - the best advice I can give is just to go, aim just to "stick it out" and accept that despite being uncomfortable it is good for your career.
The reality, is going to these dinners and parties, is where many colleagues will form bonds - especially from departments you don't normally work with. As such, missing out entirely, means you are missing a valuable networking opportunity. Moreover, just showing face, shows you care about the team and makes people more likely to see you as a real human (especially when things go wrong).
It would be a lie to say that there is no affect on your career to skip it.
So, how can you actually deal with the day itself:
Remind yourself these are the same people you've seen for the last 4 weeks. There's nothing special about them this time, you know these people and they aren't suddenly going to change.
Remind yourself that your value is your work. You have no obligation to be funny, charismatic or interesting. Coming across as quiet will not destroy people's confidence in you as an employee.
Remind yourself that how you're feeling is perfectly OK. It's a new situation, and it's crossing the border from work to personal life. Having a panic attack is OK, it's how your brain likes to deal with it - nobody will notice, and if they do it will only be out of caring for you.
Set the bar really low. Sticking it out to a certain time of night (not too early), and nothing more. You know you can manage this, all you have to do is not leave. Even if you have a panic attack - you know how to deal with these - you can just go to the bathroom and wait it out. A simple objective is something you know you can achieve.
Focus on yourself. In the run-up to the event, which can be terrifying, just focus on yourself and what you'll be doing. Other people will tend to themselves, you don't need to worry about fitting in with them or anything else. Just focus on drinking what you want to drink, and eating what you want. If you join in their conversations - great. If not - that's fine too, it's their loss not yours.
These feeling are normal when you have anxiety, but it will get better. Each time you force yourself through these situations, you'll get better with them - the worst thing you can do is cancel; that's the panic part of your brain thinking, and it doesn't control you.