Need more sex from my spouse

I've been with my man for 7 years. We've been through alot. ... alot. And a little over a year ago he cheated we delt with it.. :( we banged for what seemed like 2 weeks straight and then he just became less and less interested in sex... like he got lazier and lazier. Than I got pregnant I mean we barely had sex at this point so I know the day I got pregnant where and what position. Now we have a 5 mo old son. (Beautiful boy) and we've had sex 3 times in the last 14 months. The sexual tension is really getting to me I've become meaner and I'm starting to really dislike him. How do I get him to want to have sex with me? Please someone has to have an answer before this ruins our relationship.