I've graduated from my previous grad school (psychology) for 2 years and now seriously considering to apply for another graduate school (or professional school at master's level), computer science in particular, for next year's entry. That was also the major of my college degree. I will be applying several Canadian schools now and hope I will be able to start a new life there.
I was extremely uncomfortable when I just got into the psychology graduate school four years ago that I didn't do well at first. Not only due to English being my second language, but also I had absolutely no background in psychology, plus the massive amount of reading filled with weird words drove me absolutely crazy. For this reason, my major advisor had me finish with a master's degree instead of PhD, which I was originally enrolled in. However, he was extremely helpful when I was doing my master's graduation project and thesis. He was helping me day and night with my work that I believe nobody else could ever help his student this much. I ended up finishing my master's level of psychology very well and left with that degree.
When I got in touch with him recently and asked him to write a letter for my next school, he said
"I will mention that at first you didn't turn out to work very quickly that you had trouble to get what I was asking done. So I had you finish with a master's degree instead of PhD. However, later you learned to work much harder and your final project and program worked very well. If you think the above contents suit you, let me know where I should send the letter."
I don't know for sure if my feeling is correct, but I feel like I will get 100% rejection even from mediocre schools I'm going to apply, if those words appear on the LOR.
Question: should I switch letter?
Concern: I didn't ever think one day in the future I will need to go back to school when I was still doing the psychology program. Thus I was't enthusiastic at all about building my connection with professors so that two other members of my thesis defense committee really don't know me very well.
This is probably the last chance for me to change my fate, I don't want to lose it.
Suggestions please, and any help is much appreciated.