Sister-in-law crossed a line or two?

A few weeks ago when I saw her, she started teaching me from the moment I woke up. I've become very skilled at ignoring her or letting it all roll off but this time, I believe she crossed a line. She's always been obsessed with knowing when my husband and I will have kids but not for us, she's obsessed for herself. That morning, she started parenting my non-existent and unborn children. Telling me what they are allowed to do and what I should do in different situations. Then she said, "When you start having kids, I'm going to save your marriage." She went on and on about how detrimental kids are to a marriage but "don't worry, I'll be there when it happens and I won't let your marriage suffer". Neither my husband nor I talk to her about our personal life and marriage so, little does she know, we've been trying for a year and a half and I was finally starting infertility treatments that month. When she talks about us having kids, I can usually ignore it and it doesn't bother me but I felt that she crossed a line speaking about my marriage. So, unfortunately, I snapped and said "you have no idea what you're talking about. I start fertility treatments this week." She was shocked but stayed silent (she doesn't like being caught off guard with anything because she knows it all. And she didn't speak to me for the rest of the day. 

The following day, while I was bathing her kids, she started teaching me about my options and what the fertility specialist will do. Then, she proceeded to tell me that endometriosis is not real and that my infertility is in my head. She told me it's a good thing that we don't have kids yet because I should wait until we've been married for longer (we're going on 3 years) and wait until I'm at least 29-30 because that's how she did it and she doesn't think that certain people are good mothers at young ages. (I'm 24, almost 25) But, she said, "I'll share my kids with you for now until you get your own so that you won't be sad." At this point, I was fuming but I only said "We've been going through this for a year and a half. I think we know what we're doing" and I walked out. The rest of my visit, she had me hold a kid every possible second and she started calling me "Mama". 

I refuse to argue with her because I LOVE my in-laws and that would hurt them but, she always does this when my husband is not around. He knows how she is but, I even why I say something that should end the conversation, she doesn't stop. 

Is it just me or is she out of line?