PLEASE help ive just found out...................!!!!?

me and my bloke have been seeing eachother for 17 months and things have been a bit upside down, but we are good now, im 23 and have a 5 year old son from my previous relationship, and i live in a two bed house wiv my child, i found out yesterday im pregnant, and i have not told my bloke, i dont want a child yet as im not really a maternal person and have just got back on my feet, job, driving lessons etc. im scared that if i tell him he will be mad as i dont know what his feelings would be on this as his only 24 and is still living at his parents, and is into his cars, although has asked me to get a place wiv him, im really scared, im planning to go to the doctors tommorow to arrange a termination and not tell him, if i tell him, im scared he will leave me, i do not want another child just yet but dont know whether to tell him im pregnant anyway, i dont know what to do. please help me.