Serious dilemmas such as this is a reason why one should always have a close shayches with a Rov/Da’as Torah.
The most important thing is to ALWAYS show your love and respect for the child. Don’t ever kick the child out of the house except in the most severe cases which you should not decide yourself.
The only time you should break off contact (never completely) with a child is if they intermarry (with a proper civil wedding). However even in such cases you should still ask.