Pregnant and not sure what to do with fear over your boyfriend?

Hi,well i have been in relationship with a guy for 9 months we get on well we are a 4 hour drive away .Usually we take turns in who goes to who's place and now ive messed up BIG TIME.im 24 he is 36 and a great guy i mean it !im a single mom of a 4 year old boy and adore him and my boyfriend accepts him and almost treats him as his own but now im pregnant and scared hes going to get mad because we DID NOT plan in having baby its his baby because for my sons sake i didn't date anyone until i met him because i have tryed so hard to do what is right for my son now im pregnant again and im scared it is going to move him away from me because i love him tremendously im 10 weeks pregnant and i know it with the last 5 weeks im afraid to answer phone calls and meet him i was meant to go up to his home but had to pretend im sick im afraid to do anything i have even canceled him coming here i havent a clue how to tell him any of this i feel so bad! i love kids i really do but i cant rare a kid on my own again its really hard .hes going to freak out i didn't plan to do any of this but i just want him to understand i cant do it on my own im not getting an abortion i think its wrong but i also do not want to force him having to end up with me either .what do i do? is it possible to be a single mom of two kids? im afraid people will think im a slut if i have two kids from different fathers .what am i suppose to do i never dated a person in 3 years and now i have messed up.i dont know how to tell him im carrying his child hes going to freak because he is the type that likes to party he did ask me if i were ready to settle down but i dont know if he meant he wanted to settle down with me and i sware im not a slut or a bad person im just so confused i really mean it. im open to any advice at all im afraid all the stress will harm the baby i dont want to lose the baby nor my boyfriend what do i do.