What do i say when he tells me?

my boyfriend that i have now is wonderful.this is the most serious relationship that I've ever had. we've been together for about 6 months now and the other day i got a text from him that said "we have been together for about 6 months now. i sure do like you baby. i truly never planned on being with anyone else again. I'm so happy that your are a part of my life now".(he was with this one girl for 7 years she went to florida and cheated on him then she came back and packed her stuff and left and is now married to the guy that she cheated on him with.) im 17 and hes 21. we don't say that we love each other its more of "i like you" thing. this all started when i went to my best friends house he went crazy and thought that i was going to cheat on him. he was texting me the whole time acting all crazy. then he texted me and said "hope you know i more than just like you but im scared to push it or act to soon so i can prove that i deserve your love. this is something that i wouldn't normally text i would want to say it in person" and he always tells me that hes crazy for me and slipped a couple of times saying that he loves me. but one time i think that he really meant it because he grabbed me by my arms and looked me in my eyes and was like i love you Kasey. then it took him more than 5 seconds to correct himself. but i think that i scared him because i got a shocked look on my face and my jaw dropped to the ground then he was like i mean i like you. anyways my question was how to do i react when he tells me that he loves me. i know that my face will turn red. should i just be like awe baby i love you too?? i don't really know what to say with out sounding dumb.