How do i get over my heartbreak and loneliness as a girl?

I had a best friend who used to tell me that he loved me and wanted to marry me. At first, I didn't have any feelings for him and made that clear. However, because he was a decent guy, I told him I wouldn't mind marrying him in the future when the right time came. He even told my mother that he wanted to marry me and asked if my family could wait for him. At the same time, he would say that if I got a better marriage proposal, I should take it.
He faced many struggles in his life, and I always stayed by his side. He always seemed so happy with me and used to say that our time together was the only time he felt truly happy. We didn't even touch each other all those years; it was just pure company, and we were both happy.
After a few years, I developed feelings for him too and became certain about marrying him. However, his parents were super strict, so he couldn't give me a solid commitment. Even though he was the one who proposed first, he started backing off because of them. Still, he promised he would try his best to marry me. We were together for almost six years.
But last year, when I was upset with him over a minor issue, there was no argument or anything, he suddenly said he would never be able to make me happy and wanted to leave. I couldn't believe it at first. But the way he behaved afterward, and how firm he was in his decision, made it real. I tried for months to fix everything. Nothing worked. Instead, he became so rude that I finally stopped talking to him.
After a few months, I couldn't control myself anymore and contacted him at least to know the reason why he did this to me. This time, he completely blamed me, bringing up unexpected reasons that he had never mentioned in all those six years. He even stopped opening my texts. When I promised him I would never contact him again, he replied with a cold, two-word goodbye text. Lol. I wonder if he will even feel sad or regret ever what he did.
It has been 10 months since he left, and I still think about him and cry almost every day. Please don't judge me; I am really tired of myself too. I feel so lonely, but I have absolutely no energy to initiate conversations with anyone. I feel like I will never connect with anyone else the way I did with him. No matter what good things happen in my life, there is always a void in my heart, and I cannot feel completely happy.
Do I have to live like this forever? Can anyone give me advice or tips to get over this pain and loneliness? Regarding the loneliness, I am not looking to meet new people or make new friends. I just want to become so happy and healed within myself that being alone doesn't bother me anymore.