I don't think you sound dumb at all. In fact, I think you sound like a very bright 19 year old. Codependency is very common and I really suggest you address your codie issues now or you will spend a life time allowing them hurt you.
The book Codependent No More is a great start.
There is nothing selfish about protecting or having boundaries for you and you baby. It's called self care. Something I am just learning....much later in life.
Naranon or Alanon meetings will be a great help also. Be gentle with yourself. You had a need to know, now you do...so now what are you going to do about it???