Any idea what happened to my car?

Any idea what happened to my car

Today while driving I was about to have to make a complete stop due to a car being stalled in the road. I had the chance to go around him so I quickly accelerated to the left lane to go around him, and when I did our 2004 Chevy Impala automatic which until today had been driving fine with no indication anything might be wrong felt as if it was stuck in neutral. It didn’t want to go although the gas was being pressed. It then jerked hard and hasn’t driven the same since.

Now you can’t go even go forward in drive. It’ll even roll backwards in drive. Reverse works but when in drive it actually seems like you’re in neutral. If I go to 1 on the column it’ll go forward, then 2 seems a little rough and will go to 3 smoothly. And even getting started in 1 after being stopped at a light or a stop sign it’s a very slow process. Like it doesn’t just go. It takes a minute. Fluids are fine. I don’t know much about cars but prior to what I explained above it drove fine until that very moment. Once you reach 2nd it’s a lot better and 3 on the column above 40 drives as smooth as ever.

Any ideas what might need to be repaired? I know transmission could definitely be the issue, but just out of nowhere with no previous indications at all? I don’t know I’m just looking for some information. Thanks a lot. I’m just bummed out about it. I’ve been excited because literally next week I make my last car payment on my 2020, so to have two working cars and no payment was nice. It’s just always something 😏

Any ideas?