Thanks for your update and well done for bringing this up with your husband. I also must commend him for taking it well - there is clearly a lot of love between the two of you.
I had a friend in a similar boat to you, who brought up having an open relationship, which her husband was initially blindsided by, but eventually (years down the line) they decided that they were both happy to have threesomes with women, which allowed her to explore her bisexuality in a way that he was comfortable with. She did, however, end up “catching feelings” for a regular threesome partner, which put a halt to the whole thing.
More years went past and now her and her husband are divorced and she is now in a relationship with another man, as despite being more sexually attracted to women. She has, so far, not met a woman that she is compatible with enough to build a long-term relationship with.
I say all this to let you know that open relationships usually serve as a bandage on the wound, rather than a lifelong fix, unless both partners start the relationship knowing it will be an open one, where they have come to the conclusion as individuals rather than as a couple.
I also say this to say that like PP have said, you should only leave your marriage if you’re aware of the fact that you may not have a successful relationship with this woman or that you may end up single for many years whilst you explore your feelings and sexuality. Whilst few people will ever feel “comfortable” in this knowledge, you should be at a point where it is unwaveringly the right way for you to go.
Good luck, OP 💐