My husband and i have not had for a year, he claims he cant get it erected because of his medication, ?

am fat. I feel thats why he doesnt want to do it with me. Last year, my husband was flirting and going out with a lady, he admitted when caught...he says that she was just a friend. I did not ask him much because i was worried of the outcome. However i knew than that he was confiding in a lady. is my husband getting from elsewhere? He claims he is on diovan hypertension pill, that is why he cant get erected? He is 45 and has been taking that medicine for 15 yrs. Pls help