Repress memories

Go to the police with her and confess you made up the rape. You can learn from mistakes but you have to accept them and fix what can be fixed.

You "accidentally" got your half-sister pregnant?

Like, you jerked off in the bathroom, and she walked in a minute later, slipped and fell down, and your semen just sort of got smooshed up in her vagina?

Please. Call a spade a spade: you fucked her and made her pregnant because you both were too stupid to take steps to prevent that.

I could have some sympathy for the two of you if the story ended there, but no, you went on to lie about it to your parents and the police, and some poor, random guy was arrested on suspicion of rape. And you kept your mouth shut to save your own miserable hide. I hope you understand just how fucking despicable that was.

If there is such a thing as karma, you'll get yourself all sorted out and you'll happily live your life until you're an "old guy", and then one evening the cops will suddenly bust into your place and arrest you for raping some woman (or kid) you've never even seen. Hope you enjoy that.

I have no idea why your therapist has decided you should just forget what you've done. Generally, the best thing to do when we fuck up is to try to understand where we went wrong, make amends where we can, and move on, determined not to repeat that mistake and to behave better in future.

In your case, it sounds like you could do with learning to consider the possible consequences of your actions and how to take responsibility for your mistakes. Maybe your therapist believes you have taken all that on-board, so dwelling on your past fuck-ups is not doing you or anyone else any good.

However, the fact that you refer to your half-sister's pregnancy as merely an "accident" and how you express no remorse for what you and she put the "old guy" through suggests that you haven't really grown up. So, I don't know what your therapist is thinking. Maybe they think you're such a steaming mess that there's no hope of you dealing with your issues until you put the huge ones aside for the moment, deal with the less significant ones, then gradually creep back towards your really monumental fuck-ups.

Or maybe the therapist is a quack. There are loads of them around.

But also call the suicide hotline

Fuck no. This shrink should not be practicing. Do everything in your power to get this man out of prison. Dammit.