Sidewall damage is almost unrepairable. If it is indeed damage to the steel belts, the tire will fail violently (instantly) soon in the future.
That's a good reason not to be trying to change it on the car, because that involves a lot of direct handling of the tire. Tires can blow from handling/maintenance, and do hurt people handling them; that's why you may see your tire shop inflate tires inside a very tough cage. If he's afraid of a new tire, do the math.. But it's pretty safe in your wheelwell. So with a structurally damaged tire, ask yourself "is this handling necessary?"
Of course it's much more dangerous to drive the car normally at-speed and have a blowout cause a loss of control or vehice rollover.
But don't let the chicken littles fool you, you can limp the car to the tire shop. It's vital to keep speed down to a speed where you won't lose control when the tire violently fails, 20 mph (30 kph) will be absolutely fine. If you go much faster, energy in speed is a square function, so you have a wildly increasing chance of loss of control, rollover, colliding with other cars, hurting yourself and others, and wrecking the car of course.
Also, very important: don't just get on the main road at any speed. Don't let yourself into a situation wher you say "I am going fast because I have to", avoid those roads. Work your way through side/back streets; a longer route is fine. Choose roads where you will be able to stop immediately without disrupting traffic too badly, and once the tire is blown, you can safely handle it without fear (except of sharp edges) and put on the spare on. This will not be a normal soft tire, if you press onward for even 0.1mi (0.2km) you will quickly destroy the wheel. Road conditions won't care; I've been in places where you had to drive another 2km to get to a safe place to change a tire, and just had to let the wheel be wrecked. Don't select roads like that.