Can’t handle this anymore

My mother in law keeps trying to push me out of the picture and be mommy to my 2 month old son she is always calling herself mommy and momma to him and demanding she gets him when she asks for him or else she cries and writes a big Facebook post about how hurt she is .. worst part is we all live together so she just walks into my room all the time without knocking so I’ve been keeping my door locked but then she gets upset cause she wants to see my son. I can’t live like this I want to move and not have her in my life at all. She said she wanted to have a baby a couple years ago but my husband told her not to cause she will have a grandchild soon enough and be a grandma so now that baby is here she is living in fantasy world playing mommy with my child.. she even pushed and manipulated her way into being in the birthing room when I gave birth .. when I told her no I didn’t want her there, I just wanted me and my husband ..she told me I’m not normal cause all daughter INLAWS let’s their mother INLAWS in the birthing room while giving birth. She doesn’t even appreciate she was there either to this day when the topic is brought up she always says it’s her right to be in the birthing room

Sorry for the long rant.. she has just called herself mommy to my son too many times I’m going insane and don’t even feel like I’m the mom and that she is going to end up confusing my child by pulling this shit... she only seems to say it when She thinks I’m not in the room or close by or doesn’t think I can hear her. When I’m next to her or she knows I’m in ears reach she will call herself grandma

This whole situation is getting to be too much