Is It Safe To Have Sex After 3 Days Of Abortion?

After 2 weeks of abortion , I thought I had my period. So I had sexual intercourse and since we thought I had my period , its safe to release his semen in me . The period last for 3 days and very abnormal than before . What isit ? Am I pregnant ? Because recently ive been feeling mood changes drastically and feeling lightheaded but I did a home preg test last week its negative. After 3 days of abortion we did had sex though.help