New grad-need advice

Hi all, I’m a few months in to my first RT job. Things have been rough. Pretty much everyday I come home from work I beat myself up for how I could have done better. Lately I’ve been dealing with a lot of rns undermining me and treating me like I’m an idiot. What can I do to gain respect/trust. Ex) had a patient who was on bipap, ams, couldn’t self rescue so he had a sitter.. asked the nurse how he felt if I tried to take the pt off bipap (pt has been on for 12 hrs at this point). He looks at me and says it’s up to you… I take the pt pff and he desats on 5L. Put him back on bipap. An hour later this RN brings the doctor in to do the same thing I did, and get his opinion. Just seems kinda like he didn’t trust my opinion.. I didn’t find this out until later in the night when I tried to wean pt off bipap again. Sats were better, color better. Put pt on 5L NC sats were good for the first hr. Noticed pt desat after a while and went put him back on. When I went to do so was tachypnic and had developed a fever. Told RN. Later this pt gets intubated. Just feels like everything is my fault and the RN was blaming me/undermining me. Opinions?