How to stop recurring thoughts of loss

I'll make this as short as possible. It happened nearly a decade ago, yet it still haunts me. I've met an extraordinary person online by chance and we got close. You may call it a long distance relationship. He was on a different continent..
Not too longer after, things went downhill in my life with my only and abusive parent. As I was financially dependent, I had nothing of my own, I was forced to study a college I detested. We mostly communicated via social media and messenger. Abuser didn't let me use internet freely and tried to monitor me.

Back then, during the critical period, I had language barrier and in addition I could barely focus on what he wrote and think of a decent answer for I had always to watch over my shoulder for the abuser, so I came off as stupid and inappropriate sometimes. I couldn't watch documentaries he recommend me, so I came up with shabby excuses as to why I won't watch them. Once my peers trolled my messages randomly while I was afk and sent him retarded jokes. Half my brain cells died at reading them. He still thinks it was me.
Occasionally I had to unfriend him (during chekups) to prevent abuser from finding out about him and giving us both hell, he thought I did it playfully for fun and got annoyed.
During one of those 'unfriend days', while I was beaten and made to sleep on the floor in the hallway, he got involved with someone else in his country. He said he wasn't doing that earlier, so I felt confident about having time to put together speech about what was going on.

Per se, what he did was not reprehensible. I understand his position, BUT....
he did not notify me of this status change. He could've sent me an e-mail but he didn't. I inquired him about this. He said he lost his respect for me.
ok, but failing to notify me was his failure at basic human decency.
He had audacity to say 'we can be friends'. How can you be friends with someone after that?

I gave up on my plan of apologizing to him and confiding in him about what's going on. It took me time, great courage and figuring out how and what to say in all that confusion and agony, especially with that language barrier. You all gals know how it's hard for us isolated abuse victims to speak up about it even to a professional. Nobody ever offered me an support ever.

Distance wasn't an issue, we did get along beautifully until the abuser kicked in...He brought value and great joy to my life. Then he violated my trust and faith in him, our friendship, everything...all because writing a 1-2 sentences was too much of a hassle. I was struck thoughtless and speechless and said to him to 'have a nice life' and cut off any potential contact. We parted on such poor terms that trying to make any contact would be ludicrous. It was like losing the dearest, most beloved and precious family member, which he basically was to me. THis happened nearly a decade ago.
I've tried being indifferent, angry, but nothing works, I love him to this day with every bit of my being.

During my downs my thoughts always drift back towards him and the joy and hope for my life the abuser has destroyed. It was the last straw. My depression escalated.

How to end this grief? It drives me mad. 'Socializing more' with other people isn't an option because of imposed social isolation or eating deluxe candies (I'm still financially dependent).

I am sorry you have gone through so much abuse--that is the real problem.

It is perfectly natural that your friend got involved with someone else in his country. That is the downside about our online friends--the connections are very real in some ways but don't always translate IRL. Sometimes I feel like I live in two worlds--an online one and my IRL one. In my opinion, if you don't have good IRL friends then online connections are better than having no one at all. People need to have friends.

I am sorry you lost him. Having had so many misunderstandings must make it so much harder. I know it is not easy but I think you should try to move on even though it hurts. Hopefully, time will make it less painful. I am sorry you can't socialize. Work on getting a job/becoming financially independent. If you can figure that out then your abusers will no longer have the power to sabatogue your relationships.