Are electronic cigarettes harmful if you have COPD?

I was diagnosed almost 3 years ago and am currently on oxygen 24/7 at 4 LPM. I also have sleep apnea which they figure contributed to the COPD. I smoked 2 packs of cigarettes for 36 years before I quit 3 years ago, however, I used the e-cigs to get off of tobacco and now I'm addicted to the e-cigs. Although they don't create smoke they do draw like a cigarette and you inhale a vapor. I know one of the best things you can do to slow down the progression of COPD is to stop smoking but I don't know if the vapor from these e-cigs are harming my lungs further or not. I also have Cor Pulmonale ( right-sided heart failure) and am quite obese. All of these things combined makes life with COPD difficult and I'm worried that my use of the electronic cigs is hurting my lungs further but can't afford to put any more weight on either. Does anyone have any first-hand experience or know of the safety of using e-cigs with COPD? I'm currently somewhere between stage 3 and stage 4 but at only 55 yrs old would really like to extend my life as much as possible. I'd also appreciate any weight-loss advice for someone who is considered morbidly obese (5'4" 290 lbs) but severely limited physically, due to multiple spine instrumentations, chronic back pain resulting in mobility issues, as well as the limitations the COPD cause.