My friend has sex with a girl when he was 17 and she was 15. She is pregnant, and threatens him she will throw him in jail if he dose not be with her. He is now 18. So my question is does age count the time of the crime or now? And is it aganist the law if they are 2 years apart?

The age of consent in Texas is 17.

A prosecutor will look at the ages at the time the act occured, not the ages now. The 17 year old was at the legal age to consent to sexual contact, but the 15 year old was not.

The law states that it is an "affirmative defense" to prosecution if the actor (the 17 year old) was not more than 3 years older, and is the opposite sex, and there was no duress or force used. If he is charged for this violation, it would be in his best interests to speak to his attorney about this affirmative defense. (See the laws below, highlighted portion)

There are other issues here that are going to show up soon and will require some legal expertise. Establishing paternity, custody and child support to name a few. He has certain rights and responsibilities as the father and should seek legal advice on these matters. They can become quite complex and very messy if the correct steps aren't taken in the beginning.

Information On Establishing Paternity From the Texas Attorney General

Texas Penal Code Title 5 § 21.11. INDECENCY WITH A CHILD.

(a) A person commits an offense if, with a child younger than 17 years and not the person's spouse, whether the child is of the same or opposite sex, the person:
          (1) engages in sexual contact with the child or causes the child to engage in sexual contact; or
          (2) with intent to arouse or gratify the sexual desire of any person:
    (A) exposes the person's anus or any part of the person's genitals, knowing the child is present; or
    (B) causes the child to expose the child's anus or any part of the child's genitals.
(b) It is an affirmative defense to prosecution under this section that the actor:
          (1) was not more than three years older than the victim and of the opposite sex;
          (2) did not use duress, force, or a threat against the victim at the time of the offense; and
          (3) at the time of the offense:
    (A) was not required under Chapter 62, Code of Criminal Procedure, to register for life as a sex offender; or
    (B) was not a person who under Chapter 62 had a reportable conviction or adjudication for an offense under this section.
(c) In this section, "sexual contact" means the following acts, if committed with the intent to arouse or gratify the sexual desire of any person:
          (1) any touching by a person, including touching through clothing, of the anus, breast, or any part of the genitals of a child; or
          (2) any touching of any part of the body of a child, including touching through clothing, with the anus, breast, or any part of the genitals of a person.
(d) An offense under Subsection (a)(1) is a felony of the second degree and an offense under Subsection (a)(2) is a felony of the third degree.