How to get over an ex after years?

I've been in love with the same person for almost 10 years. I met the person in HS, years ago. And we broke up our freshman year of college. We kept in contact off/on, even through my 1st marriage which was a rebound to try to replace this person. The person had problems expressing feelings, etc so I got angry and married someone else when I was young/stupid. I am now remarried again, and while I love my husband.. I cannot let that person go. I've been to therapists, psychiatrists, pastors, etc. My husband now says I am infected by a "demonic spirit" and that I have to "let it go". He says that it will magically go away, well its been 10 years and countless dollars spent on therapy, but I still care for this person. Is it really all my fault and can go away magically, I haven't found it to be that simple. The person pops in my life every so often, they goes away again, which is weird. Is it all my fault like my husband says?