Porn/Masturbation induced ED?

Hi,

this is my first post here, and it is one in desperation. I recently discovered to my horror that I have a difficulty maintaining an erection with girls I sleep with. Let me describe the situation as short as I can.

In the last three months I had sex with three different girls (since a very very long time). One was a one night stand, when I had difficulty keeping it up, I blamed the alcohol. The second girl I had a quite some dates with, and again had difficulties, but managed to perform just enough. And now I am dating a girl which will hopefully become a relationship, but... recently had sex for the first time and I could barely keep my erection! Which was incredibly frustrating. We both are extremely sexual and this felt like a huge disappointment for her (and me too).

It feels like I lost my sensitivity. I can get erections by myself, and during foreplay, but as soon as I start the deed, I can't seem to maintain it. I figure it has to do with my masturbation habits and porn use. I am 23 years old, very healthy and active. But I masturbated with porn since I was 12 or so. And since I started college, I masturbated with porn almost daily.

How big is the chance that it is caused by this and not caused by (performance) anxiety? And how long will it take to get back to normal? I read stuff on yourbrainonporn etc. and I feel like I fit the description for a porn/fap-addict. And should I tell my girl, which is no relationship (yet)?