Have I correctly used ‘to’ and ‘impulse is’ in my sentence? Would it be better if I omitted ‘is’?

Have I correctly used ‘to’ and ‘impulse is’ in my sentence? Would it be better if I omitted ‘is’? Please enlighten me.

The boy said: “There are times when Mom suddenly gets mad. The nearer she is to me, the stronger her impulse is to hit me.”