Horror and Fascination are related, just like fear and excitement are.
The past is not fixed. It is always possible to remember it anew, in both better and worse ways, which is to say with a greater fondness that comes with greater understanding, or a greater loathing that ALSO comes with greater understanding.
If who you were then is not who you are now, then it makes sense that your understanding of that time might change also.
I will say that in all long term processes of personal growth, there will come times when you cringe at things you have done or said, that made perfect sense to you when you first did them.
And I think too you will realize there were times that seemed bad, that were not really so bad at all. Hard work and difficulty are not intrinsically bad or good, and not infrequently they lead to new insights that make life better.