This is a complex and sad relationship. Your boyfriend's issue with erectile dysfunction is a matter that can be treated by a urologist. Treatment is available if he wishes to seek medical attention. Your self-esteem and overall happiness are being compromised. I have no advice or suggestions on how to fix the problem. I don't know if this relationship can be fixed. Talking has not helped, so I don't know if intervention with a well-trained counselor would help. If you have concerns about his fidelity during this upcoming trip, then, this indicates to me that there is no trust as a foundation in this relationship.
The final choice is yours, and yours alone. But, why stay with someone who behaves this way?