Bismillah,
Asalamu Alaykom,
If by ‘sexting’ you mean explicit messages between a husband and wife, then this wouldn’t be haram provided that it wouldn’t lead to a sin. For example, if a man fears that by speaking to his wife in a sexual manner while being away from her, that it would lead him to engage in masturbation, then he should avoid anything that leads to that and wait until he is physically with his wife.
May Allah grant you success