First relationship + sudden LDR + his ex-fiancée works with him

Problem/Goal: first time being in a relationship and i genuinely need advice on how to stop overthinking 😭

Context: we just got together last month after 6 months of courtship, then had to go LDR almost immediately because of his job. before we got together, he was once engaged, 2 years naging sila bago sya nagpropose, but the wedding was called off almost 2 years ago. now, because of his work, he’s also in the same place as his ex-fiancée.

Previous Attempts: he’s never failed to reassure me naman, and i trust him. pero minsan nauuna talaga utak ko gumawa ng sariling kwento 😭 how do you learn to quiet those thoughts and just enjoy the relationship?