It is very important for you to know the root cause of your problems, and I believe most of your questions could only be answered by a doctor.
You said you have been overweight and have low sexual libido. I believe if you really want to work things out for your marriage then you too should try your best to change the situation. You can begin losing some weight by switching to an active lifestyle and healthy living. Or your problem could also be psychological which might need some therapy or counselling. You doctor might also check you for signs of low-T. Most importantly, think positive. There are also natural supplements out there you can try for yourself to improve your sexual and overall health.
I believe that communication is the most important thing for a successful relationship. Wives should learn to communicate with their husbands to resolve problems in marriage.
Men often times have the tendency to keep problems to themselves and only tell the problem once they find a solution - it's part of their ego. This is the time where women should be a good listener and understand what their husbands are going through.
Men at some point of their lives might experience sexual problems. This could be erectile dysfunction, low testosterone, premature ejaculation, or the loss of sexual drive. Whatever, the cause behind these problems, whether psychological or physical, it should be dealt with accordingly.
It is generally not safe to mix medications together, especially ed pills since this might double the possible side effects. It is better to choose one medication at a time that best suits for you. Or you might want to see your doctor to check out which medication might work best for you. You may also like to check out this article since it contains some info about ed and medications http://www.vardenafil20mg.info/health-newsView Thread