I'm in love with another woman who is married I'm also married and also a woman, she has three siblings I have none we love each other she tells me she's capable of leaving her family for me, she lives well, has a loving husband and great kids, am I too selfish??

Yes, to put it bluntly and since you have asked, you are being selfish. The kids need to be considered first - their stability in a home life with both a mom and dad, etc. Anybody is capable of being in love with any number of people. But, being married is a commitment whereas two people have made vows and promises to each other. Why would you want to even consider being a part of breaking up a happy, successful marriage if it really is that way concerning their marriage?

If she is saying that she is capable of leaving her family, that would seem to me to indicate that there is something going on in her family that is unstable. I may be wrong, but I think that there is more to this picture than you present in your post.

What about your commitment to your husband in the bonds of marriage?

I would encourage you to help her to find the ways to keeps the bonds of the family secure. This could involve counseling or other ways.

That is my opinion anyway. Hopefully, others will add theirs based upon their experience and expertise.

Yes, total agree with Clough. If you truly love her you will put the security of her family before your relationship.