Confused about Father's Actions. Is this cheating?

Yesterday I was watching IPL with my dad(55M-Gujrati) and I was sitting on sofa and my dad was sitting down on floor. My dad was using his phone and scrolling through facebook and I saw him forward a very vulgar reel to a female relative from my mom's side. He wasn't aware that I am watching and I clearly saw him forward the reel through whatsapp and saw the Contact name.

Background: My(21M) parents had LM and my mother(57-Marvari) is the one who is breadwinner of our household. She's a CA. My dad(did bcom) earned for first few years of marriage and had a business of Computer hardware. Out of the blue he decided to shut down his small business and suddenly had the thought of joining a company and doing a proper job. He earned way less than my mom and my mom supported him. When I was born, many relatives recommended that my parents hire a nanny and both work but my mom was against the idea as she didn't wanted to leave her kid at home with a nanny. She even put forward the idea that she would hire a nanny and house help if my dadi was willing to just stay with me and she wouldn't have to even lift a glass but my dadi refused and didn't even bother to help my mom much in Postpartum and pregnancy. Also my dad earned way less than my mother(his own salary could only afford rent).my mom basically had a flat and very good package through her job. My Dad left his job and raised me.

Even After that, my mom was the one who was balancing her job, my studies and household. My dad had the only job to feed me and pick and drop me from school. My mom never disrespected my dad for being house husband and gave him credit cards always made sure his bank account had sufficient funds. Before leaving his job, he only used to spend money on his family(My elder uncle was jobless).My mom built everything from scratch. Since 2021,my mom started encouraging my dad to start his career again.

Relationship of my parents: As I grew up I saw my mom and dad's relationship. My dad is verbally abusive and has a shi**y tongue. He has called my mom Derogatory curse words whenever he is angry and in even normal situations. My mom also has to use curse words in retaliation when he goes on her family. There has been 2-3 instances where he even raised the hand on my mom over years. He even punched me hard once that my nose started bleeding. Whenever my mom's sick, he always calls it a drama and facade. There has been instances where he has been caring towards my mom too. Its really confusing. He is also a big time  instigator and tries to bring friction between my mom and me. Suppose if I am out with him, he would try to trash talk about mom with me and If he is with my mom, he would try to instigate her against me. Me and my mom are aware of this thing. He even instigates my mom against her parents and he successfully broke my mom's relation with my own elder masi(my mom and masi have very sensitive bond).My mom is aware how he instigates her. They barely sleep in same room since years. Also he earns some money nowadays from his freelance jobs(Data recovery, phone reparing, hardware stuff) and he hides this money from my mom and doesnt contribute in the house. My mom never asked for his money but he doesn't even have the shame to contribute when we hit a rough patch for a year but with gods grace we are in much better position

The Female Relative Issue: So the female relative is my mom's cousin mami and my dad and mami have a 5-6 year difference. She has 2 sons(One married and one divorced) and her husband is cheating on her and everyone knows about this in my mom's side. My mom tries to keep away from her since my nani advised her to and my dad's really like into her matters. Since 2015 i guess they started talking and my dad started advising her on issues and like talks with her. During 2020-21,my dad suddenly got two phones and mom was suspicious and he told he got it from some friend for repairing and xyz and he got it in exchange for some work . During that time I found a Courier bill which had the female relative's address and i suspect she sent him those phones. Now he uses those phones to contact that lady through whatsapp and he even has a app in that phone which shows the cctv feed of the lady's house. I have seen it 2-3 times. There have been times when I heard him talk to someone in bathroom .I also saw some screenshots in that phone while he was using it. He gets really defensive and also hides when we find him talking to that lady. Like if he is in hall talking to that lady on phone and me or my mom walk in he would immediately cut the call and act like nothing happened . He also talks to her at midnight.

The screenshots had face time of him and that lady with their faces .And his gallery has xxx pics(not of that lady) .I saw these when my dad was using the phone and left it open for sometime or when I saw it by mistake. The issue is he has password and fingerprint protected phones and I cannot figure out the passwords even whatsapp is locked. He was the one who was guiding her when she found out her husband was cheating. He also talks with another lady with whom he befriended in my mom's maternal city when my mom was going through homeopathy for some backpain talks with her sometimes and i don't think there is something going on with her. The lady has a husband and grown son. She has family problems too

My mom's stance: My mom knows he talks to her mami and thinks that he has a habit of putting his nose in others matters and be mahaan insaan. He has the habit of advising people and outside he is really sweet and good guy but with us he is a douchebag. He has a different personality at home and outside. My mom even suspected and accused him of cheating but he went angry and started saying mera bhagwan janta hai i am not like this blah blah. He is religious and doesn't eat only onion and garlic, does puja paath, naam jaap (we are not Jains and cannot risk getting doxed).My dad's side is religious and they do Satsang .

My mom started thinking he is now not in touch but I am very sure he is in touch with that lady. I ask my mom how does she tolerate verbal abuses and I tell her its not healthy and she says we are family,hum mann mein kuch rakhte nahi hain gaali deke mann halka karte hain.I know this is not healthy but for her sake i agree. She is delusional that we are very happy and content unlike the others and our small world is beautiful. There was a point where my mom was tired of my dad's verbally abusive and obnoxious behavior and started transferring some of his FDs in her name(FDs were made from my mom's money) back to her. Dad doesn't know F about Finance and even when he secretly earns he asks mom to give him money and pay his credit card bills. Also even when my mom's earning he acts like he is the one earning. My mom has also lied to everyone-her side, dad's side, our social circle that my dad has started earning and he is quite busy and we have to do the drama that dad is working now and is earning quite well. My mom has good financial standing and she is independent and modern

My Situation: I am an only child and cannot talk about this to my dad's side(grandparents dead) since they are literally waiting to find dirt on my parents and make a whole circus of it in our social circle. Nana and Nani are aged and cannot risk getting them traumatized and I cant tell my uncle and elder maternal aunt. I am in college and preparing for CAT.I also got therapy once in my college since i was so done with their fights.

I am confused, tired and traumatized .I am still replaying that yesterday's moment in my head and i don't have the courage to tell my mom about this. I am also confused whether all this can be termed as cheating.

How can I deal with this? Please help me navigate this situation

Ps-This is my second or third post on reddit so apologies for grammatical errors and I have tried to fit a lot of details in above post. Also before coming at me for karma farming, I don't care about karma.

Thank you!