Chopsie your numbers are exactly same as mine bar the odd one or two.
Me personally I would not go into partnership as it would mean a massive drop in wages though I can understand your thinking that it will give you more scope to get more customers and add another income stream.
Like me you have put your all into building it so far so it would be very difficult for me to start sharing.
however if you really wanted to go ahead with this you could get him to buy into the business NOT perhaps with cash but with customers ... get him out canvassing (like you had to) and agree a target of say 80 customers over the next month or two then perhaps a partnership could be formed ... this will test his character and also boost the income for the partnership from day 1 ... however he then may choose to go alone with his 80 customers