Gained weight uncomfortable having sex with fiancé.

lala
So the past month I've put on some weight. Serious weight. I can't fit any pants & shirts are tight in belly area. My fiancé is muscular & has a amazing body, I use to. Obviously not here recently. I'm uncomfortable around him. Naked or dressed now I feel so unattractive. I don't want to go to the Gym I'm tht insecure. ... anyone have this issue ?