Dear friend,
You said two things that I find particularly compelling. Those things were "We've been together off and on for ten years now". And "I'm so tired of going through this but I've made a commitment to him."
In light of those two statements, I must ask, "What commitment exactly are you talking about?". For one thing, you are not married. It would appear that you must have doubts about his long term viability. And if you will forgive me for saying so, where there is smoke, there is usually fire.
Scripture tells us that marriage is when, "...a man leaves his father and mother and is united to his wife, and they become one flesh." (Genesis 2:24) And the apostle, Paul, warned us, "Do not be yoked together with unbelievers. ... what does a believer have in common with an unbeliever?" (2 Corinthians 6: 13 & 15) Finally, he (Paul) admonished us, "Husbands, love your wives, just as Christ loved the church and gave himself up for her ..." (Ephesians 5:25) I see no evidence of any of that where you and your "bf/fiance" are concerned.
To be blunt, yes. I believe that you are enabling him. It would seem that you need to decide whether you want to deal with this for the rest of your life. I would advise you to take your problem to God. Ask him if what you are feeling is true Christian love, or something else altoghether. Also, if you can, seek the Godly counsel of someone close to you; a pastor, a good friend who is a strong believer, or someone who is familiar with your situation.
God be with you in your struggle.