He had intercourse with his wife during the day in Ramadan, under the influence of drugs
Question

                I am married, and I used to be addicted to drugs. Praise be to Allah, Allah turned to me in mercy and I recovered. My question is: I had intercourse with my wife during the day in Ramadan on nearly ten days or more, when I was not in a normal state because of taking drugs, but I am not able to fast two months for each day. Can I feed the poor? What should I do to discharge my obligations? I have repented and I deeply regret what happened.
Praise be to Allah.Firstly:
We congratulate you for your repentance and your recovery from these evil drugs, and we ask Allah, may He be exalted, to make us, you and all the Muslims steadfast in obeying Him, may He be exalted, until we meet Him when He is pleased with us.
Secondly:
Whoever has intercourse deliberately during the day in Ramadan has rendered his fast invalid.
Ibn Qudaamah (may Allah have mercy on him) said:
We do not know of any difference of opinion among the scholars regarding the fact that the one who has intercourse in the vagina, whether he ejaculates or not, or does not penetrate the vagina but he ejaculates, has rendered his fast invalid. This is proven by the saheeh reports.
End quote from al-Mughni (4/372).
Whoever renders his fast invalid in Ramadan by having intercourse must do two things:
He must make up that day
That is because the Prophet (blessings and peace of Allah be upon him) instructed the one who had intercourse during the day in Ramadan to fast one day to replace that day, as he said to him: “And fast one day, and seek Allah’s forgiveness.” Narrated by Abu Dawood (2393) and Ibn Maajah (1671); classed as saheeh by al-Albaani in Irwaa’ al-Ghaleel (4/93)
An-Nawawi (may Allah have mercy on him) said:
In addition to offering expiation, he must also make up the day on which he had intercourse. This is the well-known view of our madhhab, although there was a difference of opinion concerning it, as mentioned above. Al-‘Abdari said that it is obligatory to make up that day; this is the view of all the fuqaha’ apart from al-Awzaa‘i…
End quote from al-Majmoo‘ (6/344-345
Expiation (kafaarah)
It was narrated from Abu Hurayrah (may Allah be pleased with him) who said: Whilst we were sitting with the Prophet (peace and blessings of Allah be upon him), a man came to him and said: O Messenger of Allah, I am doomed!
He said: “What is the matter with you?”
He said: I had intercourse with my wife whilst I was fasting.
The Messenger of Allah (peace and blessings of Allah be upon him) asked: “Can you afford to free a slave?”
He said: No.
He said: “Are you able to fast for two consecutive months?”
He said: No.
He said: “Can you afford to feed sixty poor persons?”
He said: No.
The Prophet (blessings and peace of Allah be upon him) paused for a while, and whilst we were like that, a large basket of dates was brought to the Prophet (blessings and peace of Allah be upon him). He said: “Where is the one who was asking?”
The man said: I am here.
He said: “Take it and give it in charity.”.
Narrated by al-Bukhaari (1936) and Muslim (1111).
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
Intercourse in the vagina requires expiation, and it is as if there is consensus on this matter; there are only a few odd dissenting views.
End quote from Sharh al-‘Umdah (4/284)
The expiation referred to in the hadith quoted above is mentioned in order of precedence. The one who breaks the fast by having intercourse must free a slave; if he cannot do that, then he must fast for two consecutive months; if he cannot do that, then he must feed sixty poor persons.
This is the view of the majority of scholars.
Ibn al-Mundhir (may Allah have mercy on him) said:
The scholars differed concerning the expiation that is required of the one who has intercourse during the day when fasting.
One group said that he must free a slave; if he cannot afford to do that, he must fast for two consecutive months; if he is not able to do that, he must feed sixty poor persons. This is the view of Sufyaan ath-Thawri, al-Awzaa‘i, ash-Shaafa‘i, Ahmad, Abu Thawr, an-Nu‘maan and his two companions.
End quote from al-Ishraaf (3/121).
Secondly:
If someone consumes or drinks something in Ramadan that causes him to become intoxicated, then he has intercourse with his wife, he cannot be excused from having to offer expiation on the grounds that he was under the influence of the intoxicant, rather the reason for the expiation is still applicable in his case, which is that he transgressed the sanctity of the month by having intercourse, to which is added the fact that he consumed something unlawful, so his sin is greater. >> That is because he knew, when he was sober, that he should keep away from intoxicants, but he did not do that, so he is to be punished for what he did.
See: Majmoo‘ al-Fataawa (33/103, 108); and I‘laam al-Muwaqqi‘een (5/196).
Thirdly:
If fasting was obligatory for the wife on those days, and she willingly went along with him with regard to having intercourse, even though she knew that it was not permissible for her to do that, she must also make up those days and offer expiation for them.
But if she was forced, or fasting was not obligatory for her on those days, or she was unaware of the ruling, in the sense that she thought that it was obligatory for her to obey her husband in that, then in this case she does not have to offer expiation.
This has been discussed previously in question no. 106532.
Conclusion: You have to offer expiation for these days on which you had intercourse. If you are not able to free a slave, and you have a valid reason for which you are not able to offer the expiatory fast, then you must feed sixty poor persons for each day that you had intercourse, and you must make up each day.
The amount of food to be given when feeding the poor has been explained in question no. 106535.
And Allah knows best.