Unless there's an actual medical problem already in existence or a known issue with the bladder and urethra, what you're experiencing is the beginnings of a g-spot orgasm and I agree with your husband. If you relax and let it go, it'll be one of if not the best orgasm you will ever have in your life. Just let it go, I promise you it isn't urine. (No one really knows what it actually is, but they do know it is not urine. It's very close to men's pre-ejaculate but not exactly the same combination of proteins and all that other fun stuff.)

Sounds like you're a squirter. It can take a lot of time to get use to the idea of letting it go, but it feels amazing. Put down a towel or a spare sheet to protect the bed, and take a nice shower together after if it's really that bad, but I highly doubt it will be.