#1 Your desire to avoid sex could be many things. You could be at an age where your sex drive has decreased or it could be of course be him. To have a healthy sex life you first have to have intimacy. You could work on this as a couple since the passionate stage of your relationship has passed. If you are certain that you don't feel sexual towards him then you have to tactfully tell him that. It is not fair to make excuses - to you or him. He may have a sense of poor self esteem but that doesn't mean you should protect him by lying. If you want to work on this issue then do so but if it isn't going to change anything then you have to tell him.
#2 It sounds like you are owning his issues relative to his lack of confidence. You can't respond constantly to that because it will stress you out. Suggest that he find a therapist so that his relationship is separate from the work he needs to do on his self esteem. He can't gain confidence by you convincing him that things are fine. That will never happen. He has to be okay within himself.
#3 Decide together what the job responsibilities are. Try not to do things because he won't. Give him responsibilities that aren't urgent and remind him rather than doing them yourself.
You have to decide if you want this relationship. It sounds to me that you don't want it. You yourself said that you don't see a future. So if you spend time with him and there is no future then you are wasting your time. I think you stay out of guilt. That is not a reason. He will get over the pain but you can't stay because leaving will hurt his feelings. I think you know you have lost the desire to be together. Tell him and get out of a relationship you are staying in out of obligation.
Please press accept; this is the only way I am compensated