Mitmoo. You wouldn't allow your DS to see a film that was wholly inappropriate, that would disturb and upset him, give him nightmares and traumatise him, would you?
No.
You would stand up and say NO. This situation is more serious, more damaging and more hurtful.
How about sitting your young man down and having a proper mum to man chat with him.
"On this occasion DS, I am making a judgement call, I have more insight, more experience and more understanding of the consequences than a lovely trusting and kind 14yo. In time you will see what I see, but you can't right now, so for now you will have to trust me.
going out with your father, having you end up in tears well within an hour, and needing to come back home, rightfully so, (and I am delighted that you did) means to me that as it currently is, seeing your dad is hurting you somehow.
Perhaps when you are a little older, you will feel strong enough to hold your own, but you are 14, and it's too much to ask of you right now.
We will work together, you and I and we will help you feel stronger and the confident young man you deserve to be. You will get there, because I believe in you, I will help you in every way I know how, all you have to do is be a little bit brave, and to trust me
When I see that you are strong enough and your Dad is able to treat you appropriately, and kindly, then we can arrange outings with him, but for now, you need to take a little break."