In the short term, the most important things to know are these.
You can home educate for a long or short time. If you change your mind about home ed, you can send your son back to school. If there is no space at his current school you would have to send him to a different one - but you wouldn't HAVE to home educate indefinitely. School is always an option.
You don't have to have a plan for how you are going to home educate before you get started. You can figure it out as you go along. It will take time for your son to recover from his school experiences, and during that time, most home educators recommend a break from any enforced academics - let him relax and play until he is in the right frame of mind to focus.
There are many ways to learn. You may or may not have some ideas already about how to tackle it. Even once you do think you have it sussed, more than likely it will take some experimentation over the months and years to understand what he needs and find a way to provide it to him - and his needs will change and you will need to adapt. That is absolutely right and fine; it doesn't indicate that you are getting it wrong but rather that you are responding to his needs.
You have plenty of time. Once he is out of school there is no pressure to "keep up with the rest of the class". What your son doesn't learn this month he can learn next month, or next year. When he works at his own pace there is no such thing as falling behind.
My motivation for all that I've said above is to reassure you that there is no serious risk involved in taking your son out of school. Imagine yourself removing him from school right now, immediately, this weekend, and assuring him that he never has to set foot in that school again. What is the worst consequence you can imagine?
You know that his current school is wrong for him. He is suffering. Take him out now, and see him transformed. Once he is safe, take your time to try home education or explore other schools. There's no need to wait.