Husband seems to be stalking my family

My husband deserted me 9 months ago. Recently he has been calling my son at work, asking questions about what car he is driving, and he has frequently
driven around the building where my daughter works, then has called her
asking to see the kids, and saying \'i thought you were at work\'. He has
not been paying his part of the rent, although he is on the lease, and I am
2 months away from being out of a home. Is this behavior stalking.. and do I
have a legal position to force him to pay the back rent?