Ok, the other day my boyfriend and I were cleaning our apartment, and his cell phone rang and at first I thought nothing of it of coarse. He asked me if I could answer it cause he was in the bathroom, and when I picked it up, the only thing the person on the other line said was "well"? Like he was waiting for an answer, but he hadn't been on his cell all day that day. So, I replied "Well what"? There was this long silence on the phone, then they said "Who is this, where is Ace"? I was real confused at that, then my boyfriend came out of the bathroom, and I said quietly to him, "are you Ace"? I practically read in his eyes him saying "oh crap" He then quickly grabbed the phone out of my hands and said into the phone "hold on a minute, Ich kann nicht hier sprechen." Which in German means 'I can't talk here' he didn't know I could speak some German. He went out onto the porch, and closed the door. I went to the door hoping to hear what was being said, so I gave up trying to eavesdrop and went back to cleaning, then I looked over at his computer, and saw HIS CELL PHONE, the one I THOUGHT rang. I still had my cell in my pocket. I picked up the cell and flipped it open, and it was still on. I heard him come in, so I closed the phone quickly and put it back and went back to "cleaning" I ask him who was on the phone, and he said "oh, just an old friend" I asked him about the phone I saw, which I am positive is his newest phone, and he said, "Oh yeah, the battery died on that, and I can't find the charger." I was so confused, I just dropped it there

Now, am I just paranoid, or does something not smell right? And what do I do? Where do I go from here? I really don't want to break up!

You two should have an honest talk. Your relatioship is not going to work if you don't trust him. That phone call sounds a bit suspect.

I would say to him that the mysterious phone call has made you feel a little uneasy.
Ask him, without being judgmental, to explain to you the situation and what's really going on.
Ask why he's going by the name ace... that it just seemed a little weird to you.

Ok, in case someone hasn't read the previous post, here is an up date to https://www.askmehelpdesk.com/relationships/getting-mixed-up-wrong-people-130230.html

I finally talked to him about more or less everything that happened that day, I told him I was feeling real uneasy about the phone call. I first asked him who was on the phone, and why they called him ace.

His reason was they were an old friend from school who gave him the nickname.

I then asked him why they said well? Instead of hi, or something.

His reason was he ordered him something and he was say well, as in well? Did it come in yet? I asked him what he ordered and he simply said "something for him".

I asked why he spoke german, and went out onto the porch, and his response was "why am I getting the third degree over a phone call"? I then told him I saw his other phone worked fine and I didn't appreciate he was lying to me. I let him know I was real scared I guess after that phone call.

He keeps telling me I'm paranoid, and I'm taking this phone call the wrong way. I then told him if he didn't come out and tell me the entire truth about the phone call, I was going to dump him, and with almost no emotion in his eyes, he said "well, do what ya gotta do." My heart just sank, now I don't know if I really do want to dump him or not.

It sounds to me like he's being untruthful.
His inconsiderate words "well, do what ya gotta do",
tells an outsider looking in, that he doesn't value the relationship.

You should rethink your priorities and decide if you want to continue with the relationship.

Good luck