My (28 F) *kind of* boyfriend (35 M) had another girl over at my place

This is a complicated situation. Me (28 F) and my technically ex boyfriend (34 M) have been crazy on and off for almost 10 years. We brake up and get back together way too much, which I know isn’t healthy. Well, although we’re not officially together right now, he has been living with me in my studio apt for a year and a half. We sleep in the same bed, have sex, all the things. He often refers to me as “his girl” even though I know we’re aren’t technically boyfriend and girlfriend, as that has always ended badly for us but we just can’t stay away from each other. We’re best friends and I love him so much. Unfortunately he is (and almost always is) in financial hardship so he has been contributing wherever he can, but I am 90% financially responsible for everything. Well, I found out the other day that he has been having some other girl over to MY apartment while I’m at work. I don’t know many details- don’t know how long this has been going on or how many times she’s been over, but I feel so violated and disrespected. When I confronted him about it, he didn’t try to deny it and admitted it was extremely wrong. He has been extremely remorseful and trying to make it up to me. He has always been a cheater. But this is technically not cheating. Not even sure what I’m asking, I just don’t know what to do.

Also, I am so disgusted at whoever this girl is. My apartment makes it very obvious that a woman lives here. It’s also a studio. There is no way she didn’t know that he lives with a woman. What kind of scum bag is okay with that???

ETA: Everyone has been tearing me to shreds here and that is honestly what I expected. I know I need to kick him to the curb but it’s SO NUDE. I didn’t grow up with an example of a healthy relationship, and I’m so afraid of being alone. Mental health issues are also at play. I have very few friends and this guy has been my main stay for 10 years. For those saying I’m more pissed at the girl, I started out extremely pissed at him, now the anger has just subsided to hurt. Also, for those saying I can’t be mad because we’re not technically official, I’m really just upset about him having her at MY PLACE.