It’s just you and your horse . You are one so you are a team the negative comments are what you should do to make a better team. And your horse trainer is the coach so if you r unsure about something be sure that you always check with your coach ( trainer)
Are they productive comments, or just negative ones? Are they coming from experienced horse people trying to help, or from peers trying to belittle. It really depends on the negative comments. If they aren't trying to help, I would ignore them. The equine industry can be quite cruel that way, and everyone has an opinion whether they're right or not. If it's advice, I would consider it and ask your instructor about it. I've had to give what would have perceived as negative comments before, but only when the health and safety of either horse or rider was at risk. There are more than a few who are happy to belittle people though, and them I would just ignore.