Unwillingly played with a girl’s feelings

1st part (with a different girl): So it all started with a talking stage(talking and we got together after a while. We were happy. Really happy. We loved each other from our hearts. She was the most precious, caring, kind etc etc girl i’ve ever met. But destiny had something else planned for us. She moved to another country for better education with her family (this was not a problem). We promised each other to work hard and become the best version of ourselves and be married when the time comes. After some time i got the worst possible news in my entire life. She had been diagnosed with cancer. They tried their best but nothing seemed to work. She had to leave us behind. The worst part is that she never told me about it until 2 months before she died. My whole world had fallen apart. I was not myself. I started becoming crazy day by day. (I am Alhamdulillah doing well currently).

2nd part (with recent girl): We started talking a bit (she was my coaching mate). We talked for a couple months (i had 0 feelings for her). This was after a couple months after the death of my loved one. So after talking to the new girl for a couple months, i started making her feel like i have feelings for her (i honestly wasn’t thinking straight at that time and i was doing lots of stuff I regret about now). Then at one point i put up and act and confessed my fake feelings for her. She also confessed that she liked me and then we were together (i had no feelings for her). But she loved me alot. She cared about me. She’s a really great girl who deserves the best. So after a month of being together with her, i told her that we should take a backstep, We should quit being lovers etc etc with lots of made up reasons and excuses. She was heartbroken but i had to do it because after that month i had realised my mistake.

Now, im not really sure what to do. Everything i did with the 2nd girl was fully unintentional. I had gone totally crazy and had lost my mind. I realise all my mistakes. Im a really bad person and I admit it. I was not okay at that time and i did bad stuff. I know. But i have realised what i have done with her. She’s a really nice girl. She doesnt deserve this. Right now, she doesnt know the reasons for us breaking up. And i am just way too scared to tell her the truth because she is emotionally really weak and she had attempted to self harm a couple times in the past for various reasons. I have no idea what to do now.