Before you ask your H try and get more solid proof/info.
If he has hired this person to do bookkeeping in the past he could easily say the meetings are business related.
If she is part of the homeschooling group he could easily say he is trying to become more active in the education of his children since you already do so much.
IOW, if he is seeing her he will lie and since he has legit ties (business, homeschooling) his excuses will come easy.
I know this is upsetting. Just be sure you have all the best info you can before you do anything.
