I don't have an SO, but I do feel guilt towards my family, even though logically I shouldn't because of the way they treat me. I still do though.
I would just make sure to leave a note, and explain that they should not feel any guilt or sense of responsibility for what happened, that it was your choice, etc. Pain will be unavoidable, but I think it may hurt less to have some sort of explanation. I'm also not sure what your situation is like, but I would also be sure to have your affairs in order so as to put as little work onto them as possible afterwards. If that's the route you end up wanting to go