If you're buying the sorts of lube that are sold in supermarkets, you can say it's to help when you're inserting tampons or suppositories for constipation - ie. lube has uses beyond sex stuff that might be private but certainly capable of explanation to a child.
I don't think it should be your husband's responsibility to choose lube (maybe his to buy it) - it's for your comfort and there are a huge range of different lubes available with different combinations of ingredients. The main categories are:
*Water based
*Silicone based
*Oil based
(There are some hybrids as well)
Water based = safe with condoms.
Silicone and oil based aren't safe with condoms.
Silicone lubes shouldn't be used on silicone toys unless covered with a condom first.
If you do anal play there are specific thicker lubes sold for that purpose.
Look up osmolality + pH in relation to lubes and also check lubes for glycerine - this may be an ingredient worth avoiding re thrush but I've seen conflicting info.
I've been trying Uberlube - a silicone one that comes in a spray bottle and Yes! Water Based. I didn't get much difference between the two but in theory silicone lubes are meant to last longer.
In addition to lube for sex stuff, there are some other items to consider that might help comfort wise:
*Vaginal oestrogen
*Vaginal moisturisers
*Emollient ointments
Vaginal oestrogen works locally in the vagina to give it enough oestrogen to make it less fragile / dry / irritated. You can use vaginal oestrogen creams around the vulva too. If you're under 50 in the UK a GP needs to prescribe this.
Vaginal moisturisers are a non hormonal way to add moisture to the vagina and are used regularly eg every 3 days regardless of what sex you're having. I like Yes!VM but there are a number on the market.
Ointment consistency emollients eg. Zeroderm can be soothing to the vulva and can be applied as often as you want through the day eg. before +/- after weeing, if weeing hurts.
Vaginal and vulva skin is usually quite good at repairing itself quickly. But breaks in the skin = possible routes for infection to enter. Penetration that's making you bleed / hurts with dry skin isn't the safest thing to do even if you're into sexual pain.
That takes us back to your husband needing to care about your safety and enjoyment of whatever sex stuff you're doing. If there isn't lube there's probably little scope for sex involving genitals and moving to other body parts and activities will be needed.