I get overwhelmed really easily because my feelings were invalidated my entire life so when I'm going through something I constantly question how much of it is "real"  and how much of it is just my bpd making me feel intensity towards the situation. It is exhausting to sort through and navigate every thought and decide if it's rational or helpful, and if my feelings are permanent or fleeting. 

Right now I'm struggling because I've been in an amazing relationship with the most incredible guy I've ever known for almost 2 years. He has a 10 year old son who lives with us. (his ex wife lives across the country and has been in an out of jail, and was a negligent parent when my partner was overseas)  
She recently got out of jail and visited us. Her and my partner got in an argument in our driveway about when she was bringing his son back. I went outside to see what was going on and she started yelling at me saying I'm not his mom and she doesn't even know my name because I'm a nobody etc etc  ..... 
My partner didn't stand up for me during this. 
I ended up just walking back into the house. He later  told me that I can't insert myself into any arguments because all it will do is make the situation worse. And I have to just trust him to deal with his baby mom however he needs to because she's an impossible person.  
I suddenly feel on the outside of what I thought was OUR family. His 10 year old was calling me "mom" up until now.. (Im sure she told him not to call me mom because he hasn't since he's been home from seeing her) I'm sad because we bonded so well and I did consider him my son. But now I feel like they are always going to be a family and I'm just always going to be the step mom and that makes me feel so much less important. I'm starting to wonder if I can emotionally handle this dynamic or not. As much as I love my partner I'm scared that this is causing me too much pain.