I dont know if i can live like this anymore!? MATURE ANSWERS PLEASE!?

I am a 24 year old girl living in the U.S i am originally from Colombia and and from a Colombia-Irish family. My mom & i moved back to the U.S when i was 15 but ended up going back home. I am with my partner for 8 years now and am engaged and i love him dearly. He was part of a very dangerous gang back home and i ended up leaving him as i could live with it anymore, He is now 3 years away from that lifestyle, He left so we could be together. We are both living in New Jersey near my family as my parents split and have jobs etc i finally got myself a really good job. I still go back to Colombia to see my dad, but my partner cant come with me as he is a 'marked' man there. Sometimes at night he will wake up with nightmares from his past and what he has done, i just wish he could forget it. He had so much hatred back there and lost control of his life to the gang. I feel like i don't know if i can live like this anymore. Sometimes i look at him and see him as an ex murderer that he was or whatever he did but i now see how changed he is, going to church etc. I really dont know what i should do. Any advice would be great & please dont judge me, Thank you.