Converting to Catholicism

Hello - my husband is converting to Catholicism. He grew Christian non denominational. I grew up catholic but haven’t practiced for years. I am getting all my papers around baptism, first communion, etc to the church I’m attending so I can officially become a member of the church.

My husband and have been married for 13 years. We know we need to move forward with convalidation of our marriage which is a longer process than I thought. But the church is telling him he can’t start his conversion until our marriage is convalidated. This is a little confusing to me, so if I did not want to convert or convalidate our marriage he wouldn’t be able to be catholic?