My Boss" Wife Could Not Get Pregnant For Him, Now He's Got Me Pregnant..

I work in this office and my Boss and his wife have been married for
about 11 years without a child and the wife filed for a divorce not too
long ago. We started a relationship when he came down about a year ago
and wished I could get pregnant for him.
We use to have unprotected s*x a lot but I didn't see any sign of
pregnancy so I concluded he may be the one with a problem, hence his
wife's decision to leave him. We decided not to have s*x again on the
1st of January as we both feel guilty after the act.
Now there is a problem...
I tested positive when I checked with a test strip, so I'm pregnant. 
He's very happy but I'm not. He told me he wants to go and see my family
 and have the necessary rites performed in March.
My worry is he might not do so (as promised) and the pregnancy will
start showing. I had the same problem with my first son's dad who always
 postponed the date for him to come and do the traditional rites till my
 tummy grew and everyone noticed I was pregnant yet he didn't marry me.

I suggested an abortion but he refused saying I'm depriving him of
becoming a father besides he's getting to 40. If he end up not marrying
me like my ex, my family will be very disappointed in me for allowing
such happen to me again as I can't call this one a mistake.
I'm so confused and need your advice on what to do. Can I trust my boss?