He needs to be the one to set her straight and let her know that he is with you and that she is not to threaten you (what did he say to that and when she threatens your daughter?). He has rights as the children's father. He does not have to go to where she is to see them. He should consider legal action to obtain scheduled visitation. These can then be at the home he shares with you, or out to a park for example, and she can't say anything about it. He should also be setting his family straight about their treatment of you.
He is letting her manipulate him, and he in turn manipulates you. He may love you, but it doesn't show in his behaviour. He should be with you and the child you have together, not sleeping over with her. Do you know if they are actually sleeping together? Where did he stay when he went to Riverside for a month?
If he has been sleeping with her, then it is up to you how you feel about it and whether you trust him.
Regardless, I would let him know what you need from him in how he handles this situation with this other woman. His contact with her should be regarding their children and nothing else. No daily phone calls, certainly no naked pictures sent, no sleeping over, etc.
Don't argue with him, no yelling, keep it very matter of fact. This is what you want and expect from him, is he or isn't he willing to do it. Try not to get caught up in the drama of this other woman. It might actually be feeding this guy's ego. Some men are lame and, while they may deny it, they get off on having women fight over them.
If he isn't going to be in your corner, and support you and protect you from mistreatment of these other people, he does not love you... no matter how much he might say that he does.
Once you talk to him and discuss some changes, see how he responds. Does he make excuses? Does he turn it back on you? Does he say that he will do one thing, but then does the opposite so that nothing changes? Or does he actually finally stand up for himself and for you?
How things go from here will maybe help you decide what your next move should be. You don't owe him anything. He may have helped you out before, but look what he is doing now to you, and allowing others to do to you. I'm not seeing much of anything that resembles honest and mature love.
Talk to him... see what he says and does. Then you will know how much he really loves you... or not.

