So I got my first ever betta today, and the pet store i got him at was very cruel to him

i think he may have a little bit of fin rot... but anyway on the way home the bag he was in randomly burst!! He was flopping around and didn't have any water left in his bag! I had to put him in a plastic water bottle to live, and the water in it was pretty cold too

I got him home safe now, and put him in his bowl, but he is acting strangish and I'm scared he may die of stress due to the near death experience he had today

. also anyone know any good places to buy good silk plants? the place i got my fish had none so my fish is desperate for a place to hide!
I hope some fish experts have some advice for me on what to do about the fin rot, and also the stress!