I think its entirely normal to feel concerned the first few times. I would say guilt is probably a little too fat, perhaps unknown regret...
If were honest, theres a (extremely small) chance that you might pass covid onto you parents and therefore a chance they might become very ill/die. Depending on where you live this could be a very very small chance.
However, few people are knowingly or willingly infecting friends/family. Instead you're meeting parents with good intentions to support them and you're children's wellbeing.
I would argue as a parent there are times I have willingly risked my children's life more. Ran across a road with them, left them in the bath as a baby whilst I grabbed something from bedroom etc. All minor things, but things that cause guilt, only unlike meeting grandparents there was no real gain and I have done them several times. That's not to say that I should have done those things, but when you consider the risks you may also have taken (different to me of course) seeing your parents has some perspective.
What might help is a conversation with your parents about what could happen. Are they happy with the risks (death) and could they/you cope. I find very few people seem to have these open conversations (mostly ad they put it down to scarmoungering) but once you have it makes things easier.
We have met my parents several times, including then staying over for several nights and us going on a shared house holiday, but we spoke about the risks (much earlier on when I feel there was a greater risk than now) are at peace with them.
Most importantly though. Speak with your husband.