I can only speak for myself but l am constantly looking at everything from all angles so feeling guilty comes with that. To give you an example, mum hurt her ankle earlier this week, bad enough to call an ambulance, anyway while waiting l was working through all the scenarios including ....if she goes into hospital at least l will get a good nights sleep.
.in the end she didnt go, we weighed up the distress of A&E or a wait and see strategy ( which seems to have worked) but now l feel bad that l might have chosen something selfishly, luckily l didnt but trust me after a week of little sleep it was borderline.
I think the point l am trying to make is try not to feel bad, we have fleeting thoughts that come uninvited into our heads, a natural weighing up of any situation 'fight or flight' and l am almost positive that you had reaaons for feeling relief that it is finally over, l know l will when it eventually happens. Dementia is awful from both sides of the fence and l know given the choice mum wouldnt want to carry on for years like she is.
Be kind to yourself, take time to remember lovely times, its ok to miss someone so try not to dwell on the guilt, relief is understandable x