Hey! I'm sorry you'll be having to spend time in prison, but I'm glad you're using the opportunity to better yourself. Here I tried giving you an idea of things you can do. I saw you are interested in compci/programming, but as you of course know, these are pretty difficult without access to a computer. So I think it is perhaps better to focus on math for the time being and get strong in that.

The way I see it, there are two paths available to you in studying math, and that is a path which involves proofs and one which doesn't. Proofs give a much deeper and more satisfying outlook on math, but they are also not so easy to learn. I would definitely give proofs a try though, knowing how to prove things might help you a lot in computer science, although if you end up not liking proofs then there's no harm done.

If you want to give proofs a go, then the first book for you to do is "Velleman's How to prove it". You might want to combine this with multivariable calculus, for which I usually recommend Lang's calculus in multiple variables, but if you like Stewart that works too. A good proofy linear algebra text would be Friedberg's Linear algebra. For discrete mathematics, I recommend Rosen. And for differential equations, Simmons is a nice book. Also interesting (but not that related to CS) would be to get your hand at a copy of Euclid's Elements, which is a book of 300 BC which tries to do geometry from scratch. It's excellent to get into proofs and to also read probably the most influential book in the history of math and science. If you do choose to get it, be sure to get a book with extensive commentary since some part of Euclid are not so easy to read.

If you're not so interested in proofs, then you should start with continuing calc 3 from Stewart, together with discrete mathematics from Epp. Then you should do differential equations from Boyce Diprima.

If you're interested, I have a small online study group on discord, where I try to help interested people self-study math. If you wish, you could join us and we can discuss a bit further what would suit you best!