I have three active alcoholic aging and impoverished brothers who I have a codependent relationship with.
I dread contact with them because it usually includes a request for a handout.
Something you might consider is that you may not be his only source. I was surprised to find out that my bros ask for money from just about everyone. (!!!!!)
It's their game.
I am not suggesting that your ex has other gf's, but I have seen my bros develop codependency everywhere and with anyone, anytime. Their friends, other relatives, take your pick.
In other words, you may not be the last gas station on the highway. So, I wouldn't worry about that.
The other thing is that if you help him, you may just be prolonging the misery and preventing the effect of the consequences he seriously may need to feel. Hitting bottom is what brings many people to the door of recovery.