SurvivingInfidelity.com^®

Well, I actually officially found out the day before.
Prior to finding out about this, we had some issues involving an overly friendly co-worker and Snapchat, and his still having dating apps in use. When we first got together he was very nonchalant about me getting into whatever I felt like, his stuff or electronics, but I had never really felt the urge to.
After we had been living together for a few months, I noticed that he was being more distant and he started being more secretive. I assumed it was due to work related stress, he works a lot and his job has always been really important to him. And for a while I was distracted by my mom's declining health and getting her into assisted living.
I started noticing an increase in phone calls while we were in the car together, none of which he would answer. He kept brushing them off as spam. And then I noticed some of the calls were from a saved name with a woman's name I didn't recognize.
Finally one night, the Tuesday/early Wednesday before Thanksgiving, we were cuddling in bed together and he fell asleep with his phone open on a game.
I was going to power the screen off when he got a text from the same girl who had been calling him. And she was saying she loved him.
I'm not really proud of going through those texts, but they made it pretty clear that this woman and him had some kind of relationship. They talked about going out to dinner, meeting up with showers together, making plans for birthday celebrations. Even a fight where she thought he was involved with other women and him assuring her they were in a relationship.
I didn't read it all, I didn't save anything. And in the morning when he went to work, I tried to pretend like everything was OK because I was picking my mom up for Thanksgiving and I didn't want to ruin the holiday.
He ended asking me about it that night when we were alone in his car, and I asked him who she was. He claimed she was from the past, that they might've gotten a little flirty, and that she had started taking it too far. And then he blocked her.
I never really got more information from him, he would shut down or get upset with me if I wanted to talk about it. I'm afraid to push things because I want us to be able to move on from this.
Things seemed to be getting better over the last month or so, distance disappearing and what have you, so I felt optimistic about us coming out the other side still together.
But last night I noticed he still has tinder on his phone.
I don't know what to think, or do.
I'm so sorry this post is so long.

Do not be sorry for the post, read everything, you have been heard.

A committed guy does not flirt.
Girls do not send "i love you" and "shower" texts to a guy they are not intimate with.

He lies openly to you while you read the message exchanges. And he is not on Tinder for job interviews.

Even if we say "He just lies to the other girl about being in a relationship with her because he is really with you" does not make it any better (by the way, want to bet that someone like this would say the same to the other girl?).

I am sorry you are facing this stuff, trust your instincts, not the words.
He seems really the kind of serial cheater for what I read

If you read the stories here you will see these patterns of lying, inconsistent excuses, it is always the same pattern.

Preserve your emotions and your peace. Confront him, you need clarity, you seem involved, but you spotted already red flags.

I think your instincts are right, do not suppress them, do not trust, lies from cheaters are very weak but he will gaslight you as you were crazy. Then it will collapse.

We are here to support you