First step: You need to stop thinking "dirty" and start thinking more "playful" and "sensual".
You need to introduce bjs as part of a sexual game. Don't force her. You need to make her like bjs.
Go buy yourself some flavoured condoms. Chocolate can be good. Make sure they taste good. Then tell her to give you a bj with that condom on. Give her praising while she does it. Tell her where you like her to lick you. Teach her and make her feel that she can be an expert in bjs and giving you pleasure. Make her feel good for making you happy with words. Women we like words... tell her how good she is.
Associate bjs with sensuality and expression of passion of how much you like each other... and you can even make it kinky. One day tell her to give you a bj without a condom with whipped cream maybe? Give her lots and lots of praise. Don't cum in her mouth if she doesn't want to. Respect that.
At some point bjs will be part of your sexual routine and she will be more relaxed about them. Praise her everytime she gives you a bj. When she will be comfortable ... then bring it up as an idea to start finishing on her body after the bj ... so you get her used to like it. Try it in the bath or at the shower first so she won't get put off by the stickiness of cum.
At the final stage introduce finishing in her mouth as something new to try... Get her excited. Tell her that in life... you should try everything once

... Make sure you eat lots of pineapple so you taste good.
It is all in her head that finishing in her mouth is revolting or bjs are revolting. Once she done it then she will be more alright with it.