Abortion thoughts

Although I know there are many different views on whether abortion is "right" or not. But that is not what I'm coming to discuss so if that's what you want to comment about please disregard this post. 
I have 2 children ages 2 & 3 and married their father last year. We live a very positive life but have had a lot of issues with my relatives regarding our relationship throughout the years. We decided to start trying for another (our last and then I would get my tubes tied) which was successful but since I've been having behavioral issues with my oldest child. I began regretting my pregnancy and can't seem the shake it. I'm thinking that I want to abort this child and not try for another, leaving us with 2 children. I don't know if this is healthy for me to be thinking this way, if it'll only get worse if I don't make the decision to abort. 
Has anyone ever been in a situation like this? If so, I could use some advice.