boyfriend thinks he makes me cum but I use a vibrator?

So my boyfriend thinks he makes me Cum and I give 40% credit to him. However EVERYTIME we have sex, I need my vibrator on my clit or else I won't cum. So really, my vibrator is making me cum
Not him? Believe me we've tried using it without a vibrator and we did for 1 year but I had my first orgasm with him and every other time after that with my vibrator. He can't make me cum at all, and it's annoying so I've been hooked on to my toy for 5 months or so. should I tell him my vibrator is doing the work not him? 
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UPDATE: he says "I can make you cum" or "I can't believe I made you cum" and that's why I'm asking if I should tell him