Someone I know tried to get me fired 24F

Someone I know gave a call to my insurance company, claimed they had a conversation with me, where I said that my disability claim is entirely false and that I am looking at other opportunities to take advantage of the system for as long as I can so that I can keep collecting disability benefits.

I did something stupid: a two day training during my claim with a different company towards the end of my claim, after which I was going to be on unsupported leave with first employer. I was going to leave my first employer for specific reasons. I had good reason to think my position was at risk (I received a few calls about my manager sharing concerns with my colleagues and her superior). I then came clean to my first employer's HR and shared my concerns. They recommended progressive return to work and a potential position transfer if I can find one on our carreers site. They knew the reason for my claim and knew who my service providers were too. My performance changed drastically when I went through a personal event, which is why I left initially on that leave.

I had to resign in the middle of their investigation. They said the call worried them and that they couldn't share who it was. They appreciated my cooperation but I'm almost 100% sure I was going to get fired.

I had to protect my future work applications, and was advised by people in my field who have been in it for over 20 years that this is the best thing I can do for myself.

Is there any way for me to find out who it is? I read that it might be possible if the call was made in bad faith and to harm one's position/reputation or benefits etc.

I lost my only source of income and I'm currently trying to find a job. I'm extremely scared and sad that someone who knows my personal situation, and who knew I was potentially quitting took advantage of the situation to make it seem like fraud. I did do the training and took full responsibility for that, but what was added was incriminating and false. I'm losing sleep and my anxiety spiked as soon as I got that first call about this, the waiting time was even worse.

Only close people to me knew of details, which is scarier.

I will not make a mistake like this again. But I can't help but feel paranoid of the people around me. If I am able to know who it is in a legal way, I'd like some advice.

Thank you for reading.