It is not permissible for your husband to repeat that act again. However, you do not become unlawful for him because of this act. The reason is that
breastfeeding which affects marriageability must take place during the first two years of the baby's life. This is based on the Hadith in which the Prophet (peace be upon him) said:
"Breastfeeding relationship is only established when milk is the only food (of the child)."
The Prophet (peace be upon him) also said:
"The only breastfeeding that affects marriageability is that which satisfies (i.e., fully satiates) the stomach and takes place before weaning."
Accordingly, you are not prohibited to resume marital relations with your husband.
As for the husband's saying: "You are to me like my mother", if his intention is to establish a prohibited marriage relationship based on breastfeeding ties, it will be of no account. However, if by saying so he intends Zhihar (a man likening his wife to an unmarriageable relative), he will have to offer Kaffarah (expiation) for Zhihar, which is to emancipate a believing slave. If he cannot find any, he must observe Sawm (Fast) for two consecutive months. If he cannot do this, he must feed sixty Miskins (needy persons). This is based on the Ayah (Qur'anic verse) which reads:
And those who make unlawful to them their wives by Zihâr and wish to free themselves from what they uttered, (the penalty) in that case is the freeing of a slave before they touch each other.
(Part No. 21; Page No. 103) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.