In a bit of a pickle... Please help

So firstly a little about myself. I have two beautiful children. 7 and 5. I'm only 24 myself. I am not with their dad nor have a been for four years. I'm studying to be a nurse and am half way through my degree. I started dating a man about two months ago. It is still new and fresh. I found out that our condom failed us and I am one month pregnant. 
Now I am not against abortions. When I found out I was pregnant at 17 I considered that option. I have a lot of close friends who also choose this option. I just never thought I could personally overcome it. All of my friends have advised that they think I should take this option now... I am so confused. I know this is the best option but at the same time everytime I think about it I am an uncontrobaly sobbing mess. I love being a mother. I am good at it. My studies being on hold isn't a problem for me that's life. I'm very good at getting through whatever I need to.  My boyfriend has said he thinks we should have an abortion as we have only just started dating and he is worried about money, us breaking up, stress ect. All valid reasons to be scared. I'm worried he won't be able to handle this.. And will leave me. 
And then I'm left to raise 3 kids by myself. Which I know I could do. It would be hard and difficult 
 But I also feel I would never find someone to settle down with because who would want to marry a single mum of three... I am torn right down the middle of what I should do. All I can think about is what if I had choose abortion for my first child. And all the wonderful moments I would have missed... And if I choose abortion now... I'm giving up all those moments with this child... Please... Any advice would be fantastic. Has anyone been in a situation like this before? Any single mums of three?  I am just lost...