I live in Texas, I want to sell my home. My question is if I am the
primary owner, borrower and loan holder. We're married at the time of
buying house and I added my wife name as joint owner.
Now If I want to sell Do I need to involve my wife also and requires
her signature to sell the house ?

Wow! It must have been one helluva row to make you even *think* about
selling your home without involving her!!!  Ethically, morally,
intellectually ... of course you need to involve her. Legally ... who
cares.

I just sold my home, which is in Texas.  I bought it before I married
my wife and did not put her name on any of the papers.  When we sold
the home, she had to sign everything I did.  I asked if I could just
sign, but was told in Texas as long as you were married, a home is
common property.

Yes, she must sign the papers. In fact, she must sign all of them.

What will be the situation, if the wife is out of country ?

If Cynthia (who is very savvy on legal questions) says that she has to
sign all of the papers, then she does and needs to get them notarized
at a US consulate.