My (28F) Boyfriend (26M) fapped to his ex after I asked him to come to bed.

Bf of 3 years and I currently live together and have a 1.5year old daughter. This is going to sound weird but our walls are super thin. After I asked him if he wanted to come to bed with me and he said no, I literally heard him masterbating on the PC, which is right outside our bedroom.
I have no issue with porn as long as it is not to exes or Facebook people we know ect and he knows this. I was curious as I don't normally hear him and he has always said that he doesn't watch porn because it looks too fake...he even has said this to friends so I believe it.
Today I looked at his PC history and open was old messages to and from his ex from when they were together, with pics of her nudes open in history on Facebook. This crushed me. He knew how I felt about jerking it to real people, let alone his ex..
Is this something normal? I know he wouldn't cheat with her but this feels like emotional fuelled fapping and I feel betrayed. It upsets me that instead of coming to me he chose to look at his ex's nudes. As a recent new mom to his baby girl, I already struggling to accept my new body and we rarely have sex due to the baby.
Any insight whether I should get over myself or have a talk with him?
TL;DR: bf chose to masterbate to nudes of his ex instead of come to bed with me. It feels wrong and I feel hurt but don't know if it is worth bringing up or getting over it myself. Should I ask him to delete her as friends and delete her messages and pics or is that too extreme?
**UPDATE: So I gave him a chance to tell the truth. I asked him if he uses Facebook or real people to get off, and he promised me that he didn't, not knowing what I already knew. I said I know it is awkward but you know you can tell me anything and he still denied it. So I told him to delete the girl, the messages and showed him this thread. We have not spoken much since and I am struggling to not feel worthless and get past this. He has deleted his ex and 7 other girls on his Facebook that I am guessing he also had nudes of that he uses So he not only masterbated to his ex's nudes, but lied to my face. Apologies I am not sure how to do a proper update post on mobile.


Source.