Two ways for him to win:

- hit one of his outs (14) on the turn and any card besides one of your ten outs on the river (44 - 10 = 34)
- miss on the turn but you don't get the boat (45 - 14 - 7 = 24) and hit one of his fourteen outs (14) on the river

Dang it. In the second scenario, there are only thirteen outs on the river, since another of the diamonds is dirtied by the blank that hits on the turn.

That makes the new percentage 39.8% for him to win. I hope that's correct.