Hi!
I am sure you can do it! During the reboot I learned, that using porn doesn't just affect myself, but the people around me as well. This made it even more important to stop and make a change to my life. As you say yourself, you are embarrassed to talk about this with your girl and it is very likely she already feels, that something is amiss but can't put a finger on it.
Your life, and especially your love life, is bound to improve, if you get rid of porn. Your sexual energy will be redirected more towards your partner, that alone will make things better for you. Porn is not the root of all evil, but it drains your energy which is surely better used elsewhere.
How do you plan to get past porn? Do you want to do it cold turkey? Do you have a plan on what to do, if urges come up? What are you going to do during the times of the day you usually PMOed, since you should replace porn with something else.
Some suggestions to help with urges are working out or taking (cold) showers. The important thing is to actively step away from the situation, the urge will get less strong after a while.
Good Luck!