My thoughts:
1. Sleep training is never your only option. You never HAVE to do it. You can always choose to keep going as you are going. WIO is a real option and there is support available if that's what YOU want to do.
2. You don't need to feel guilty or blame yourself for your baby's sleep. You haven't spoiled him. You've been responding to him and that's great. Plenty of babies, with the exact same parenting, sleep much better than your son does right now.
3. If your gut feeling is that there is a medical problem with your son, then get it checked until it has been ruled out to YOUR satisfaction.
4. CC and CIO are not the only options for sleep training. Other people have mentioned some. There is PUPD, leaving LO in the crib no matter what, shh/pat, gradual retreat, etc etc. All sleep training works like this: you remove the sleep association that is currently disrupting their sleep, so that they learn to sleep without that. It's up to you how much or how little you want to help him in other ways. Different things work for different babies, so you may have your heart set on one method but find that it actually is making things harder for your LO rather than easier. But it's up to you what you want to try.
5. I don't believe that CC or CIO causes any damage to babies or to their relationships with their caregivers. But YOU are the one who has to believe that. It is totally normal to have ambivalence about putting your baby through something challenging. But if you really believe that sleep training will harm your baby...don't do it. You are the mommy and deserve to parent with integrity. Keep seeking more information. Do it when you feel like it is the right change to make...and then commit to doing it for a week. If now is not the right time...fine. Maybe later. But if you do feel ready to take this on, there are lots of us here to support you, and chances are it will work.