AITAH for making a move on my best friend's ex?

I (18M) had a huge crush on this girl a few months back when I was in high school. But the situation was that I knew she was never gonna say yes anyways so I never got the courage to make a move or ask her out. Eventually, with the hope of leaving no regrets, I texted her asking for notes and that flourished our friendship. We became good friends over time having similar interests and all. Now, fast forward a bit, my best friend(18M) revealed that he was talking to this girl and they were getting close. Being a good friend, I actually helped him (kind of became the third wheel) and eventually they started dating. After a few months, things became tense between them. Eventually they took a break and shortly broke up. I was supportive to both of them as they were good friends to me and I tried a lot to help their relationship but it just didn't work out. Now, in this process, I consolidated her and we came closer to each other. So close that she started sharing her personal stuff with me such as her diary cut-outs and poetry that she wrote but was too shy to post. We used to talk a lot for next 3-4 months and after plenty of time we were casually talking on call at about 2-2:30 am. She suddenly got angry that I don't share much with her and I am emotionally not opening up and it seems one way between us. Now the situation got a bit tense and I admitted that I do have a crush on her and stuff. I was actually planning to ask her out soon anyways. Then she said no eventually when I actually asked her out as well because she didn't want to get into the quarrel with my friend group again and her ex being my best friend was too much for her. I respected her decision completely and stopped pressing too much. Slowly we disconnected as it was awkward for us to continue being friends. Now there came a point where my best friend got to know I had proposed so I explained the situation to him and he was fine with it. However, we are a group of 5 friends and we go out everywhere together and stuff. A few of these guys didn't like me proposing to this girl and starting talking behind my back about me not following the bro code and stuff. They are now cool with it but whenever we go out they bring this up at-least once as if I've committed a crime.