I am sorry you have these struggles. My opinion on all this is probably going to be unpopular but here goes

1. He does not owe you rent as you can’t ask for it retroactively. He didn’t pay rent because you allowed him not to pay so you can’t really ask for it now. It’s like giving a gift but then asking person to pay for it. Plus it was a long time ago. You didn’t charge rent then and can’t ask for it now

2. $25000 is a lot of money. If you took it as a loan it’s a loan. You can’t really ask for all of it be forgiven. If you wanted money given to you, then it wasn’t wise to ask for a loan. It’s a lot of money

3. It would be nice if he supported you but most people have zero interest in supporting others. He isn’t your husband or brother or son or father. He is a boyfriend who you don’t live with and don’t even see much. He clearly does not feel like supporting you. Most people don’t want to support other people unless they are related, are a family and other person became incapacitated or something. I’d not support boyfriends. No way no how.

4. I understand you supported him at some point. But you did so willingly so he does not owe you for that. And how long did you support him? He gave you 10k loan 10 years ago at age 21. So it sounds like he was already getting on his feet then, at young age.

5. It sounds like he is doing very well financially. But unless he won a lottery or stole that money, he is earning it. He likely works hard. It’s his. It doesn’t matter if he is a billionaire. It’s his money and he doesn’t have to give it to other people even if it feels like he should

6. It sounds harsh that he charged you interest for a loan. But most people don’t just give others 25 000 with no guarantee for it to be paid back. Most people don’t lend that kind of money to anyone. So charging interest might not be that unreasonable

7. This relationship sounds unhealthy. He doesn’t sound like a good person. I am not sure if you are still in a relationship. It sounds like you two are not seeing each other. Might be time to move on. Not sure what to do with huge loan. If you still have that money, give it back. If you spent it, then I am not sure what to do. But regardless of the money issue, this relationship doesn’t sound right. You can’t make people to do things they don’t want to do and become who they aren’t. It’s better to just move on