It amazes me how many people walk into situations like this...
I would never walk foot into a dealership of any kind without a plan in hand.
If I am walking in blind, I know for a FACT that I am not purchasing today. If I am just looking around, that is all I do. If I absolutely fell in love with a used model, I would talk with my bride away from a salesman and do research and determine my approach from there.
But, I don't walk in blind. I know exactly why I am going to a dealership and exactly what I want to see. I know exactly what comparable prices are and will not be taken advantage of. I would NEVER allow some dealer to get me so upset that I thought I was having a panic attack. If I got annoyed, I would simply walk away.
I know exactly which trailer will be my next. I have spent almost a year researching it. I know what colors I want, what options I want and the maximum price I will pay. I know the MSRP from the dealer and I have already received online prices from reputable dealers. When it becomes time to get serious about buying, I will give my local dealers a chance to make me a good offer.
No pressure, no panic attacks, no nonsense. Sorry you went through this OP, but you need to have a better plan in place ahead of time in the future...