Is she cheating? I am Broken

I suspect my gf of cheating with a particular guy. Last night she went to a bar with friends and I stayed home.

After a few hours had passed (about the time she would normally come home on a weeknight) I decided to drive to the apartments where the other guy lived at. (When i met this other guy last week we discussed how he lived in the same complex as we had before.)

I had a general idea of where his building was. I circled the complex once and felt like an idiot...she was not there.

As i pulled out of the gate I saw her car pull in and she was alone and on the phone. I pulled over in a secluded spot and called her...three times no answer.

My phone rang it was her... through the conversation this is the end product..."She is still at the bar and is going to hang with her friends until they are ready to leave but she doesn't know what time that would be"

I tell her i love her and then say goodbye. As I turn the corner her car is headed towards my direction and as I pass she pulls into a spot (this is two seconds after she lied on the phone to me about being at the bar).

I park the car and approach her in the parking lot Q: I say what are you doing A:"going home" Q:Why are you at this apartment A: "I was visiting a friend" Q: When you calledme were you at the bar? A: "yes (this is a lie obviously she was already through the gate into the property)

I never let her know of who i suspect and she finally admits later that night at the house that it was the coworker she was visiting.

What is killing me inside is how she won't admit she was cheating. That night she says "that she was only going to hang out with him", "she had never been there before", "she was not on the phone when she pulled into the complex" (I saw her on the phone), & "he had no idea she was stopping by".

This morning she admitted that she did text him to ask if she could stop by. However she had said he didn't know she was coming and her phone history was conveniently deleted.

I understand if i sound controlling but i never accused her of these things i just followed my gut feelings and God did I want to be wrong.

I just want her to admit she is cheating. She denies it and says that she is afraid to tell me that she was going to hang out with a guy without me around.

This relationship is going on 5+ years and we have talked kids marriage and buying a home.

Please any advice I am Broken