Sounds like you have a lot going on with your thoughts

First, don't ever give the Devil so much control over you. I have felt like a failure at times and I was almost in tears. But in reality, I just gave the Devil a strong hold to hold me back. So please - first tell the Devil he has no right over you and needs to leave!
Next, I would really assess the placement chart for your son. If he places solidly in CTC, that is honestly what I would do with him next year. HOD is written so that kids do a lot of stuff independently. And even though they have suggested age ranges, most kids I know don't do the program at the lowest age range necessarily. Some kids can but not most. CTC may state that a 4th grader could do it but it is a lot of work for a 4th grader! I know many people who automatically plan to use it for 5th or 6th and several members on the board use it for 7th. Also - the books selections chosen are written for various ages. The creative writing was written to a 3rd-12th grade level. Apologia can easily be 6th or 7th grade stuff. And the way HOD uses it is so much better than just doing the History Notebooking. Those Tiner books are written for junior or senior high students to use for science. As for Diana Waring - I know many people who use this for junior high or even 9th or 10th grade. So the books are solid, will interest your son, and will still be age appropriate.
Also - with HOD, the neat thing is that because it is written for different ages, it can easily be adjusted to meet your child where he is. If he is a descent reader and just hates to read, I can honestly say the HOD books are fantastic. I have kids who are not readers at all and they love the books! If he can read and can read quickly, I would probably have him read the extensions. That will bring the workload up to his grade level. But if he is going to struggle with completing the extensions, I would probably skip them this year.
With Draw into the Heart of Reading (DITHOR) I would pick books that are his grade level. Since he isn't familiar with the program I would probably do the level 4/5 guide unless you think he can handle the daily writing with level 6/7/8. If he is a good reader, then you have many options for picking book packs. DITHOR is schedule 3 days a week for 35 weeks so you will only need to complete half of a book pack a year. If you wanted to get him caught up a bit, you could do all 9 books in a year if you wanted. But I probably wouldn't do all 9 books if you do the extensions - especially since you said he hates to read.
As for grammar, I would move to R&S. I don't know what level he places at but I also wouldn't worry about that either. If he places at 4 or 5, then I would just do 4 or 5 and complete 1 level a year. Once he gets to high school, you would then move to completing 1/2 a level per year. Wherever he finishes he finished and I wouldn't worry about it. R&S is very rigorous. So you don't really need to complete through 8 to benefit from the program.
If MUS works, I wouldn't switch. I would try to balance your day with him and his math. I would hate for him to get burnt out and then lose steam from exhaustion. You could definitely go to doing math 6 days week if you need or you could do math over the summer and that might help him get caught up. I would just like to encourage you though in not switching around much. If he is still in elementary math, have him finish with MUS before moving to pre-algebra and algebra. Many people I know who use MUS don't use it past pre-algebra. So that would be a good shopping point. You want to check out Foeresters or start researching but I would try to not jump around. That makes math hard on kids when there is too much jumping. Also, I think as long as he finishes Algebra 2 by high school, he should be fine for math for college. Others with graduates can chime in here. So I don't know if that will help you or not.
Another really neat thing with HOD is that is it written to 4 days per week. What some have done to complete more levels is they do school 5 days week. If you did this, you could finish CTC - MTMM in 3 years instead of 4. Then that would give you time to do 3 out of the 4 high school guides. However, that isn't necessary either. There are many members here who have modified Rev to Rev and MTMM to make it high school worthy and they will only complete 2 of the high school guides. So that is a fantastic option as well. If I were you - I would probably just complete CTC without the extensions next year then the follow year do R2R with extensions. For 9th and 10th grade I would do Rev to Rev and MTMM with extensions and modified to meet other high school electives (like Spanish and Logic). Also with Rev to Rev and MTMM, you could see if your son is ready for high school lit. If yes, you could get the WG guide and up and follow their English plan. If not, then wait. And then for 11th and 12th grade, you would complete World Geography and World History.
I think even though doing CTC may seem like a step back, it isn't! It is a good program and it will challenge your son but not overwhelm him. Since you said R to R might be doable, it makes me think it might also overwhelm him and he may struggle through. You want avoid overload because they are learning a ton of skills, not just the materials studied. And I think completing CTC will help him build some confidence for the future years for the when the workload does get more challenging. I would try not to get hung up about not finishing all of the levels. Many members on here won't finish all of the levels for each child because they have combine kiddos and that is totally fine!
I am sure others will chime in as well and give their thoughts. I do think your son will LOVE CTC! I absolutely love HOD and am so glad we found this gem of a curriculum.