Wife's Previous Addiction Affect Custody

My wife just came out of rehab and supposedly clean.
We are now separated. I have pretty much raised our son 90% and provided
care while she struggled with addiction for 2 years plus.
Will her previous addiction favor my custody percentage of child?

Would it at least give me legal custody to make church, school, and medical
descissions for our only 4 year old?

Your ex’s addiction will certainly be a factor the court will consider in making a determination of her visitations rights. I would say that your role as primary caregiver and sole decision maker over the past two years would weigh heavily in your favor as far as legal custody goes.