This is not shyness and it is not introversion
The distinction sounds academic and it changes which advice applies to you, so it is worth thirty seconds.
Introversion is a question about cost. Being around people uses energy, you run out, you need to recover. Nothing is threatening, it is just expensive, and the fix is pacing.
Anxiety is a question about danger. Your body has classified a room full of people as a threat and is preparing you accordingly, which is why the symptoms are physical: the heart rate, the heat, the blank mind, the certainty that leaving would fix everything. The fix here is not pacing. Pacing an anxiety problem means avoiding, and avoiding is the fuel.
Plenty of people are both, and they take introvert advice for an anxiety problem, which produces years of carefully managed solitude that never once gets easier.
Avoidance is the engine
This is the single most useful thing on this page.
Every time you cancel, the relief is immediate and enormous. That relief is a reward, and your nervous system is an excellent student, so it learns that avoidance works. The next invitation arrives with a slightly higher bar. Then higher. None of this requires a bad experience to happen; the dread grows perfectly well on its own, fed entirely by the fact that you keep escaping before anything can disprove it.
So the pattern is not that you are anxious and therefore stay home. It is that you stay home and therefore stay anxious. Reading it in that order tends to reorganize the whole problem, because it means the thing you have been doing to cope is the thing keeping it in place, and it also means you have far more leverage than you thought.
You are forecasting badly in two directions
Anxiety makes two predictions and gets both of them wrong in the same way.
How likely it is. The specific catastrophe you are braced for, going blank, being visibly nervous, someone deciding you are strange, is rarer than the dread implies, and much of it is invisible from the outside. People are dramatically worse at detecting your nervousness than you assume, mostly because they are occupied with their own evening.
How bad it would be. This is the bigger error. Suppose the worst version happens and you say something odd and a stranger thinks you are awkward. Trace it forward honestly. Nothing follows. There is no consequence, no one tells anyone, and the whole thing is gone from their memory before they reach the parking lot. The dread is running on a scale calibrated for real danger, applied to an event whose actual worst case is a mildly bad twenty minutes.
Confidence is not the entry fee
The plan most people are on is to wait until they feel ready and then start. That plan cannot work, because the readiness comes after and only after.
What actually reduces the fear is doing the thing while afraid, enough times that your body updates its estimate. Not white-knuckling one enormous event, which usually backfires, but small repeated doses that are slightly harder than comfortable. The goal for a given outing is not to feel calm or to make a friend. It is to have been there and left intact, which is the only evidence that counts.
What to do this week
Choose structure over freeform. A room where you have to mingle is the hardest possible version and it is the one everyone attempts first. Pick things with an agenda, a task, or a roster: a class, a league, a volunteer shift, a book club, a climbing gym. Side by side is easier than face to face, and when your hands are busy your mouth has less to prove.
Make it recurring. One-off events put all the pressure on a single performance. Something weekly means a bad night is just a bad night, and it means you are recognized by the fourth visit without having done anything socially impressive.
Take a job. Bring the snacks, set up the chairs, keep score, work the door. A role answers the two questions anxiety asks loudest, which are why am I here and what do I do with my hands, and it gives you a legitimate reason to talk to everyone in the room.
Shrink the unit and set an exit. Twenty minutes, then you are free to go. Commit to the arrival rather than the duration. Leaving early after showing up counts as a full success, and knowing you can leave is often what makes staying possible.
Arrive early rather than late. Walking into an empty room and watching it fill is considerably easier than walking into a full one, even though every instinct says to show up once things are underway.
Put your attention on the other person. Anxiety pulls attention inward to monitor how you are doing, which is the same attention you need for listening. Deliberately getting curious about the person in front of you is not a social nicety here, it is the mechanism that stops the spiral, and it works in real time.
Send the text before you can negotiate. Specific invitation, day and place attached, sent within about a minute of thinking of it. The draft you sit on for four days does not get better, it just gives the fear time to build its case.
The physical side, briefly
Sleep and caffeine move your baseline more than people expect. Going into an evening underslept and overcaffeinated puts your body most of the way to an anxiety response before anyone speaks to you.
Alcohol deserves a specific note, because it works, which is the problem. It genuinely removes the fear for one night, and it also prevents the learning, since the experience your nervous system files away is that the room was survivable with chemical help. Over time it quietly becomes the price of admission, and the underlying fear stays exactly where it was.
When to get help for it
Roughly one in eight people will meet the clinical criteria for social anxiety at some point in their lives, which makes it one of the most common conditions there is and one of the most treatable.
That last part is worth taking seriously. Cognitive behavioral therapy and structured exposure work well for this specific problem, often within a few months, and medication helps a subset of people. This is not a case where treatment is a vague long-term project.
The reason to act on it now rather than later is that untreated social anxiety does not usually announce itself as a crisis. It just narrows things, one declined invitation at a time, until the life it leaves you with looks like a series of reasonable choices you made. If the thought of a specific invitation produces genuine fear rather than mere reluctance, that is the signal, and it deserves better than being handled alone.