Twins exposed to drugs in utero

Hey everyone. My husband and I have been trying to conceive for over two years now. We've done a lot of sperm test and based on those we can only get pregnant at this time by invitro. Although many people use this method to get pregnant it is not where my heart is at so we have been thinking about adoption and have been asked my very close friend to adopt twins. They are 2 months old but have been exposed to Meth, opioids (including heroin) and marijuana. One of the babies had a seizure in the hospital and is on medication. We love these baby's and have been in their life since birth but we are both (most husband) scared of the long term affects associated. Please give us any advice, comments, or experiences.