What should i do?

Ive been with my partner for 4 1/2 years, I finished him 3 weeks ago yesterday as I thought we werent getting on & were wanting different things. (im 21 and he is 39). He begged & pleaded on his knees & cried for me to give it another go, so I have done. I then felt I had let myself down as I didnt stick to my guns. I told him i eventually wanted kids and marriage which he was against having kids but told me he'd give me one and marry me, which my responce was that i cant do that to him, let him give me something he doesnt want isnt fair. I have now planned to leave him on 6th July (set a date as this is the only time I can move) my plan was to leave him a note as i cant bear to see him go through that again, I love him but I want to go out & have a good time, not worry about having to be home for someone else. The sparks gone, I think were more like mates but the longer im drawing this out the weaker im becoming and am losing my backbone to do this. Advice please.................!xx