You sound like you're going to cheat.
I would never be with a male who has "joint custody of a dog" with an ex gf.
You shouldn't be seeing your ex, she shouldn't be coming over your place like that unless you have kids.
Whoever bought the dog should keep the dog. Either keep the dog permanently of or permanently give it away. Cut her off completely, then move on from her.
You shouldn't even have a gf with mess like that going on.
Why ?
In my defense, there's always a possibility of me cheating. This situation isn't anything more tempting than every day life.
Ex came by today to pick up all her stuff...no shenanigans. But yeah...I'm never gon' stop being her friend. shyt we've been friends since we were kids.
My next gf (if there is one) won't even know her and I were a couple
That's not right.
If that girl is so important to you that she needs to stay in your life, then you should go be with her or stay single until she isn't important anymore.