At this point, the damage is already done. They hate will still remain, her kids will be bullied even more on the basis that their mom can't even hold a relationship together (because it will be her second break up in a row after her husband), her relatives might still not accept her because they now know she's bisexual... it's a big mess actually. So, if you are going to break it up, you HAVE to go through everything, literally everything. Let everyone know who you are, starting by her relatives, and tell them that you two are breaking things up for her reconciliation with them. If you leave her in the middle of everything, it's just gonna make things even worse for her.