Agree with other posters you don't sound like a witch - you sound like a lovely person who has a few insecurities. They are obviously real and important to you, to make you feel like second best.
I would say try and speak to your husband again, but as understanding and lovely he is, this may be something that he would feel hard to understand and empathise with. Is there anyone else you can speak with who would understand?
I know how difficult it is when you want everything to be 'perfect' and somehow it just falls short. I feel the same sometimes. I had my dd when I was 17 and her father buggered off shortly after she was born. She is 11 now, and a lovely girl, and I have a lovely dp and stepson, good job, nice house and good prospects for the future, all the rest of it. But I still feel that I have failed her because I haven't provided her with a family in which she can grow up with both her parents, I had to work full time from when she was very young so I missed being at home with her, all that kind of thing. And when I have tried to talk to people, they just look at me as if I am mad!
I can't offer any advice other than please, please keep reminding yourself that you are not second best, you are a good person (stop calling yourself a witch for one ) and try and stop the niggling thoughts creeping in.
Also, one thing that may help, with your stepson perhaps try and have some one-to-one with him - just you and him, perhaps soemthing regular that just the two of you do together. Then you can build a relationship wth him and maybe develop a closer bond.
Good luck!