The first is wrong simply because you should not use due to unless it follows a conjugation of the verb to be. In that case, substitute because of, or recast to the more cumbersome, "It is due to personal reasons that I cannot ...."
I always find it easiest to remember a rule (especially a silly rule like the due to one) by finding a common example that is wrong, and remembering that it is wrong: Due to circumstances beyond our control - is wrong.
Your second choice is fine.
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