I very much recognise this fear of clouds. During initial training and reading Pilot magazine etc one is told that death is almost certain if one flies anywhere near, let alone inside, clouds.
For example see:
YouTube
I have had an IR for 30+ years but I still have a background worry "should I be here" when inside a cloud even though I have never had any trouble staying the right way up on instruments.
Like all fears they have to be conquered by doing it, start simple and build from there.